I got the Noreve case for N900 yesterday. Good quality product, just like all Noreve cases I've had so far.

Can't really say about making phone calls, as I've not yet called or received calls with the phone in the case.

The phone is held in place by a rim around the case and is actually quite firm. Access to different buttons is still provided. Texting SMS's is also possible, as the screen slides out of the case without any problems.

Noreve are also coming up with a another case for N900, soon probably available from the website.