Nothing as yet.
The car is the best Impreza I have owned.
I have owned a 1994 wrx turbo and a 1995 STI that was heavily modified.
This car was unmodified when I bought it and it was still quicker than my previous STI, I have put the usual dump valve, de-cat exhaust and induction and it eats my mates Sapphie cosworth for breakfast! Sorry cosworth owners, but the impreza is a far better car - cossie were good in their day, but to outdated now.
I have had no problems with the car and with 76000 on the clock it is still going strong.
I'm looking forward to getting a P1!
Very true, the 4X4 system on the scoob is brilliant and with prodrive there are a lott of sub 5 second WRXs now. I have one, 261 bhp 257 lb of torqe combined with AWD = neck snapping performance. From a standing start it will whip a modern BMW M3 to 60 and I was doing 120 before he passed me. Very good value. These prodrive WRXs are a wolf (that beats STIs) in sheeps clothing.
On a reliability note, my 2004 Impreza RS (the base model) has been extremely reliable except for some minor trim problems. Although I think Subaru should upgrade their interiors for the price they are charging, I think my next car will be a WRX or STI (we don't have ProDrive version in US). They seem to have the whole package (handling, speed, reliability) which seems to be a rare commodity these days.