Buy it now!
1) ABS - I'm not 100% convinced this is a legit problem yet. I've put over 10,000 miles on (at least 10 different) WRXs on bad roads, good roads, dirt roads, racetracks and I have had it happen once (when I was trying to provoke it, over a speed bump). It certainly is either perhaps a tuning issue or an ABS "feature".
2) decelaration noise - turn the stereo up while you wait for the tranny to break, then see your dealer and hope they haven't got the "memo" yet.
3) drivers window - not a terribly common problem
4) clutch shudder - doesn't affect all cars
However, the power steering problem is pretty common. On my new car, I snugged the lines down myself.