My review/comparison, for what it's worth:
My 04 WRX wagon was great, but I was pretty excited to get into an 09 5dr WRX. Personally, I think the 09 5dr is really nice looking even though some say it's the ugliest WRX yet (not a huge fan of the sedan though). With the new looks, more power and some new options I couldn't get in my first WRX, I was ready for the change. For the record, my driving is 50/50 highway/city, with a lot of bumper-to-bumper NJ traffic in the mix. I drive conservatively 75% of the time, only romping on the gas and taking hard corners once in a while. I don't track or autocross.
On the test drive my impression was that the 09 felt more solid with less road noise and was more comfortable overall. My wife immediatley commented that the car was quieter and didn't sound like a tin can as did the 04. I imagine this is due in part to the upgrade from frameless to framed windows. Sunroof and heated seats were nice to see in the premium. The hatch area looks more usable without giant strut towers. I didn't beat on the test car but it definately felt quick. Transmission felt like it shifted well enough, if a little rubbery (although much longer throw than my factory short-throw on the 04). I was expecting interior quality to be much worse having heard much complaining about it... I thought it was fine.
So I traded in my 04 WRX 5dr for an 09 WRX 5dr Premium. I've had the car over a month (i think 1500 miles maybe). I think I can give a useful review at this point and some comparison to the 04 for people considering a similar change.
There are quite a few shortcomings in the 09 WRX - some i was expecting, some i was not.
Interior quality is so-so as I expected. I have occassional rattling in the dash - haven't tried to find/fix it yet. Without a high quality feel, it makes me nervous when they add things like an electric hatch handle. I prefer stuff like that to be mechanical and failsafe. If you want to add electric bells and whistles - how about auto down for *ALL* the windows. Auto-up would be nice too. Sunroof controls are clumbsy compared to other cars I've been in that are more 1-touch style (in the WRX you have to hold the toggle buttons down for a few seconds to open/close/vent).
The radio sound quality is pretty bad even at moderate sound levels. Stock systems rarely sound *great* but this is one of the worst I've heard. Changing out the head unit helps significantly - if you just change the speakers it'll probably still sound like garbage so I wouldn't bother with the speakers unless you change the radio also.
I think the seats are softer than in the 04. At first I was just thinking how it was more comfortable, but having taken some corners at reasonable speed, now I find the seats way under supportive. I imagine they would be unacceptable for someone who races/autocrosses. I heard the STI has the same seats (with different seating surface). If that's true it's a tragedy.
The shifter is pretty long throw and isn't what I'd call 'precise', but it's not too bad. It gets into 1st at low speeds better than my 04 ever did. Something I didn't notice until a week of driving, was that reverse can be a bitch to get into. Very annoying at times, such as when manuevering in a parking lot or parallel parking on a busy street. Others have also noticed the issue with reverse. Also on the topic of shifting, the clutch pedal is really light - too light. I find I have a harder time blending than i did in the last WRX and can't always tell where the pedal is because I don't feel any pedal resistance.
I think the throttle also seems a little touchy maybe? Biggest annoyance with the throttle is a strange 'bug' in the drive-by-wire system that I noticed a few weeks into ownership. The engine revs will rise (or fail to fall) when you're inching forward in traffic and you let off the gas and push the clutch to the floor. It sounds/feels very unnatural when it happens. I've seen posts where WRX drivers say people give them dirty looks because it sometimes sounds like you're revving your engine for no reason while sitting in traffic or at a light. My dealer says there is no listed fix for the issue. There are about a hundred people posting about the problem on NASIOC. I hear this is an issue on the STI also. SOA should really sort this thing out.
There's also this new hill-holder nonsense. I cannot believe it's not defeatable (from what I read it's only defeatable on the STI). If the car senses you're on a hill it keeps the brakes engaged when you let off the clutch to keep you from rolling backwards. The concept is either genius or ridiculous depending on your point of view. I think if you can't start off on a hill without rolling backwards, you need more practice. It's not rocket science, just muscle memory. The problem with the system is that it holds the brakes too long and often prevents you from going forward. It also seems to activate when on what I would consider level ground. Before I knew what was going on, I kept thinking there was a rock or a stick under my wheels when I'd try to get going. I've stalled a few times thanks to this 'innovation' and I could see it causing more dangerous situations than it prevents. Over time I've gotten somewhat more used to it but I still would rather be able to turn it off.
Driving the car at highway speeds and around entrance and exit ramps for the past month, I've decided the suspension is indeed too soft. I heard comments to this effect but initially I thought it was great. Feels much more comfortable around town. Now I feel it's a bit of a liability. At high speeds I feel like the car's too disconnected from the road and maybe a bit unstable (at least compared to my 04). One cloverleaf exit ramp on my drive home has some bumpy patches and if you're going around the ramp at a good clip and hit some bumps, the car totally looses composure. I can't see racing/autoxing this thing without suspension mods. It's annoying that the car is low enough to bottom out the front lip on my driveway entrance but not tight enough to take hard corners? Worst of both worlds.
I've read that the 08+ WRX has open diffs in front and rear, whereas past generations had a viscous LSD in at least one axle? Or something like that. I personally will probably never know the difference given my driving tendancies, but it's kind of sad to hear that something has been 'downgraded' in your new model car.
I recently started noticing dreaded paint issues. Two little patches on my hood look very strange... almost like they're starting to bubble. There have been several chips on my hood since the 2nd week I had the car. While that could certainly happen to any car, it's worth noting that my wife has essentially the same commute as me and her 1yr old Audi has no such rock chips. And she tends to do a lot more speeding than I do.
Rear visibility isn't so great - the rear window is kind of short. I pulled the headrests off the backseats in my 04 to clear the way a bit. Not sure if that will make any difference in the 09 but I might give it a shot. I never have anyone back there anyway and it makes it easier to fold down the seats too.
Of minor note - the buttons on the new 09 remote seem too easy to hit. I accidentally armed/disarmed the alarm several times with the remote in my pocket with random stuff pushing the buttons. Now i get worried when walking away from my car in a parking garage and putting my keys in my pocket... gotta make sure i don't accidentally disarm it before i head off to the office all day.
Before I get pegged a hater, I'll get to the good stuff.
I really enjoy a bunch of the new interior options. Heated seats and sunroof are so common these days that I was upset I didn't have them in the 04. Glad to have them now. The center console has an aux input for the radio and a power plug, which is very convienent. Standard USB input would have been even better but when you upgrade the radio (which I strongly suggest you do) you can get USB/iPod/iPhone input with the new head unit. Steering wheel mounted controls for radio and cruise are more useful than I would have thought... very happy to have them and VERY VERY glad that my Pioneer replacement headunit had an available black box to keep the steering wheel controls working :-) thanks George.
Two MPG meters, one for each trip meter, is very useful. I have one tracking my overall milage and one tracking per-tank. I'm getting ~24MPG in my mixed driving now that I'm out of break-in. I think that's a little better than I ran in the 04 but that's based on estimates using gas tank size and range-per-tank. Auto-climate control is a big improvement over my 04's manual controls, and I read that the A/C gets shut off automatically under hard acceleration. Not sure if that was true on previous years?
Heated windshield wiper rest is pretty freaking sweet. Can't wait to see it in action this winter in the tri-state weather. Why don't I see that on more cars? I heard the side views are also heated but i haven't seen that in print anywhere (haven't looked).
I think there's more room in the cabin - feels like slightly more legroom and more headroom over the 04 (although I haven't checked numbers). I think the back seats might be more useable. Hatch has a better layout with smaller towers intruding with suspension bits, but I don't know if it's any bigger overall. Cargo cover is approximatly as ghetto as previous one. There used to be a sneaky little cut-out under the false floor where you could store the cargo cover in the 04 when you had the seats folded down. It was very useful and I didn't notice anything comparable on the 09... i'll have to do some more looking around.
The car feels very civil with respect to noise and ride comfort. Again, I credit the framed windows in the doors - which may also offer some added security over frameless. Speaking of security, my 09 included a security system with some sort of starter defeat I believe. Not sure if that's a Premium feature.
The little touches like red-stiched "WRX" in the seats and on the steering wheel make it feel just that little bit special. It's noticably faster than the 04 with a more useful powerband, but I guess that goes without saying. Passing that slow SUV or 18-wheeler on the highway is a lot easier. Even with a conservative launch (ie. no clutch dump) the 09 hauls off the line, which is really nice for merging on short entrance ramps and making yourself feel like you got your money's worth :-)
As fas as looks, I think my black WRX looks mean as hell...even without the bellbottoms... umm ... i mean fender flares... of the STI. Just kidding. I love bellbottoms.
Overall, it's a good car at a reasonable price offering speed, AWD, Subaru reliability (minus the paint, anyway) and the versatility of a hatch. Sometimes I miss the raw connected feel of the 04, but for a daily driver I think the 09 is a better car all the way around. Biggest down side has been going from a paid off WRX to a ball-and-chain for 4 years :-(