Yeah, show me any marque of car that doesn't have some problems.
Of all the problems you stated, none affect the reliability or the performance of the WRX. Your WRX will still be more reliable than 90% of the cars out there. Cluch shudder is common on all cars with clutches. AWD just magnifies it.
The ABS is the only valid concern you have. You just have to get used to Subaru's version of ABS. Its not bad and just as safe once you know how its going to react. You should always practice panic braking in a safe enviroment in any car to learn how it handles. It sucks to find out how your car really brakes/handles for the first time during a real panic stop or manuver.
If you want that kind of "perfection", go spend your money on an Accord or something. You can't expect a $24K car as fast as a WRX to be perfect can you? Its pretty damn close though