I think everyone on here would agree, the new S3 has lot's of pro's:
Lower emissions - so lower tax band
Better economy - though would love to see how the managed this.
Standard arm rest
Better tail lights
Better bonnet crease
Slightly more flared arches (apparently)
Though, some changes, right now aren't quite so cool:
Bigger wing mirrors
Less aggressive bumper and front fog light inserts
Errr, that's a about it actually.....
Anyway, I have the old one and am seriously considering upgrading mine early...... toying with another S3, but maybe sportback this time..... maybe...... though RS5 next year........ who knows!