Just got mine. Here's my experience...
Let the car warm up on the drive / forecourt and wait to see if the fans engage. Mine had an overheating issue due to the fans not kicking in. Luckily it was spotted prior to purchase, a replacement Mishimoto fan kit and fitting will be nearly £300.
Also listen out for noises from the rear which could mean the drive shafts need repacking with grease, not a pricey job but you may aswell get the seller to pay for it eh! The driveshaft is hollow carbon and can make it sound much worse than it is too, one garage diagnosed this as a gearbox issue needing a rebuild!
Gearbox is notchy straight from the factory but after 1 week of ownership I can confirm that once you have gone a few miles and everything has started to warm up it then it improves. Clutch bite is also quite high on all the ones I drove (not a clutch on the way out).
Petrol flap can be stubborn to open on some cars so double check it pops open with just one press, again not a pricey fix but why should you have to pay.
It is common for owners to brighten up the interior with vent trims, they are self adhesive but some owners used glue to make sure they didn't peel off so if you want to remove them it may leave marks.
The wheels are prone to laquer peel so check them for finish as you may want to respray them.
On the whole though awesome cars and great to drive, don't be put off by this list just try not to buy with your heart (not something I am good at to be honest).
Good luck.