I moved on to a 997 S a few months ago, and have put 11,000 kms on the car since then in very "spirited" touring. The car has performed flawlessly and feels absolutely bullet-proof.
It's not a 996 — but I have also driven 996's — and absolutely do not understand the comments about the air-cooled cars somehow giving a "purer" Porsche driving experience. The air-cooled cars are rougher and don't handle as well and are slower. If that is the purer driving experience you are looking for—I would encourage you to consider a TR3. You'll find that really pure.
I enjoyed my air-cooled Porsches over the years. I've owned 14 of them. They are lovely cars. But they are dated. Porsches evolve, and the new 997s IMO have every bit of the design purity and the famous "Porsche feeling" of the earlier iterations — the ultra communicative steering, the powerful engine behind you, the beautiful engineering, the rail-like handling, those colossal brakes — its all there in spades. If you haven't driven one in anger—you owe it to yourself to try one. It will convince you that the newer cars do represent progress.
As for durability—the water-cooled cars have been around for over 10 years, and there are some very high mileage examples out there. There is no evidence of which I am aware that these cars are any less durable than previous generations. None. If anything the opposite appears to be true. (The RMS problem can be avoided—and if not, there certainly is a fix.)
Gratuitous pic of my mount:
