I've recently come from a 350z which probably couldn't be more different to my '54 GTi. The zed was awesome on the right road, a proper involving, mechanical and quite raw experience but I couldn't hack the lack of practicality, poor ride quality and terrible road noise.
I do miss the exploitable RWD handling, the quick steering rack and most of all the superb brembos (oh and that v6 noise is irreplaceable) but the GTi still impresses me with how fun it is every time I show it some twisty roads. It's not as sharp a tool, especially as mine is on 17's, but the balance is great and grip is very progressive. The best bit is when you want to switch off 'hoon' mode it instantly becomes a cosseting, silent and economical cruiser.
In various guises I've owned every mark of Golf platform over the years from 2 upwards (Mk2 Golf, Mk3 GTi, Vento, Ibiza, Octy vRS etc). The Mk5 has the familiar family traits but I would say is the best all-rounder so far.