I currently have an r26 F1 in Liquid yellow, fantastic cars. Things to look out for, cam belt ( every 5 years or 40k) Renault wanted £1200 to change it. Specialists will do it for between £500 and £600.
Engine mounts- They sag, try a bit of wheel spin if the wheels judder then they probably need changing.
As most people have said, electric windows.
The dash board can make a squeaky noise- spraying silicone sorts this out though.
Lots better than the clio 182, which I have also had.
Ironically I am considering going back to a 350z but am a bit worried that they are not as quick or as fun to drive.... It's been a good 4 years since I've driven a zed but I've had 3 of them and driven at least 30 for a few weeks each.
Once you've got your r26 let me know what your thoughts are!