I think the s3 is pretty decent value when you compare to the competition, especially when you look at the banding for emissions, I think audi have been pretty clever (or lucky!) to pitch it in band f, when most of the competition is in band G. Service costs and intervals and insurance costs also figured highly in my purchasing descision.
It was between a used M3 , a used z4m coupe, or a new S3 for me. The s3 won because I just couldnt face £1000 service bills every year (although I guess theres no guarantees that wont happen with the s3), and being raped by the govt in car tax and future emissions based taxes that they havent thought of yet (I keep my cars a while these days).
edited to add: I wouldnt spec one up to silly amounts of money though (£30k+ IMO), and I wouldnt pay list price for one, but those both go for any type of car. As a general rule, any extras you add are worth nothing at trade in time.