As said above, DSG really does give the best of both worlds. Convienience on the drag to work and around town in traffic, flick the paddles for instant manual overide for hooning around backstreets when taking shortcuts and knock the lever across for spirited cross country drives. I love mine and this is coming from experience of a long line of manual VW's (Golf MkI and MkII 8 and 16 valves, MkIII VR6, Golf 4Motion, Passat 1.8T's, etc.). It copes with all situations well making the GTI a true all rounder in my opinion.
However, the advice to try both (preferably back to back) before deciding is invaluable!