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Short answer: it might be a really good deal. The EJ22 turbo engine is really solid, and the car should be fun to drive even with the 4EAT. Plenty of WRX parts bolt right on, so there are cheap upgrades / spares / repair parts around. I don't know of any "blows seals" issues, but after several years expect some oil leaks from the cam seals, valve cover gaskets, etc.
And don't put synthetic oil in a high mileage engine that has been running non-synthetic for it whole life-- unless you want more oil leaks.
Look for rust around the wheel wells, most of these cars have some there. The sunroof might leak, you might have rough idle, and a couple other quirks, but don't be scared. These things can all be fixed or lived with.
If you put some research and effort into it you will be rewarded, they are great cars to live with.