Hi,
I had an 07 roadster (313 version) which I've just got rid of. I came from a 2.0 focus (130bhp). Basically so long as your careful you won't have any issues. I triggered the ESP system a couple of times (on purpose) just playing with the throttle on an empty industrial estate. In normal driving you won't trigger it I doubt.
Well you can deffo snap your neck back (as my dad found out the 1st time I took him out and didn't warn him) as they aren't slow (0-60 in 6 or less) but they are heavy cars. 2nd gear runs to over 60 (on an 07). On the motorway you've got plenty of grunt. If you drop to 5th for example acceleartion is pretty damn swift. I never found it lacking but it's style means you can make swift progress without canning it or driving like a numpty (it's a big (ish) displacement engine so pulls well throughout the rev range).
Brakes are awesome. Seriously powerful.
A UK GT car gets heated eletric leather seats, cruise control and BOSE (6cd auto changer, tape deck, 200w+ amp & 10" sub behind drivers seat) over standard. Most people go for GT due to resaleability (a lot would be put off by cloth seats for example).
My exhaust was standard and was loud enough but if I had kept it I would have gone Nismo - think it's about 800 quid for one.
My tyres had 3mm left all round after 8000 miles. Some have said as low as 5000 others have got 12000. Depends upon make (mine were Bridgestone RE050A's).
The Z was the 1st car I had where I hardly listened to the stereo. Bose tend to skip a fair bit on the CD's and in the end I used an itrip. Please note that no Aux input or ipod link (direct) available as far as I ever found - some maybe in the USA but not sure they are UK BOSE compatible. Also the 12v power (it has 2) are in rubbish places tbh.
Imports are not neccesarily the same spec (make sure it has Brembo's for example). I would say however prices are plummeting at the moment and there are quite a few to choose from - so I guess be picky.
Paintwork - the achilles heal of this car. Paint is very thin and picks up stonechips/marks/scratches big time.
They are generally reliable (mine had 1 problem) and there are a few specialists around that you can use (main dealer prices for brakes etc are crazy).
Remember whilst it's a simple car it's big, heavy and thirsty. It's longer than you'd think (try A4 avant size or bigger), it's very wide. It prefers 97+octane fuel (but motorway miles you can get suprisingly good mpg).
www.350z-uk.com is a good place for info and friendly folks on there.
Hope that helps.