My mk5 is an 06 and I've never had an issue with it. The 'common problems' list is pretty small all the same. I have nothing but positive experiences with the car.
Mine's an 06 too and I've had no problems so far.
The list of 'common problems' on the 05 that I know of is:
steering rack
water in rear lights
failing high level brake light (v expensive)
corroding boot handle/badge
rattle from centre of dash
white worm in Monza 2s & centre caps (still a problem)
front seat folding mechanism on 3-doors
wind noise around driver's door (3 door only?)
engine rattles like a diesel.
Mostly minor, but more than you'd expect from a VW. I'd go for an '06 onwards if I were you.