the 225's are quick, i had a seat leon with same engine and that had a revo remap on it and it was seriously quick....problem is those vag turbo engines lack character. the noise is dull and the revs fade out at the top end so fun factor is low. the Z is a quick car...not that spritely off the line but 3rd, 4th gear it pulls hard, you wont be dissapointed. its power is very linear which is quite deceptive because obviously there is no kick in the back like with a turbo.
the Z is very torquey low down so no problems there and you can rev it freely which i much prefer than a turbo.
the noise alone will sell it to you!!
reliability...it is very good although there do seem to be standard faults with virtually all first phase cars (see warranty threads for details).
cost of ownership...servicing is very cheap, insurance aint too horrible, road tax about to be a real wallet clencher and fuel consumption aint great. i dont see over 24 but i drive it to enjoy it.
all in all, its a excellent second hand buy, its not the cheapest and is certainly not very practical but thats why they are still fairly exclusive unlike the ubiquitous TT.
for those reasons...go for it!