I've just part-exed a 2006 997 Carrera S for a new TTS (plus a cheque, of course!) and I'm really pleased. Okay, so it's not quite as good in corners, sounds less fruity and is a tad less fast, but it's still a really good drive and is vastly more refined.
The main reasons for changing was that, great car though it was, the 911 cost me £3k a year in running costs (less fuel) and I was losing well over £1k a month in depreciation too. The TTS also does 50% more mpg and is in a lower CO2 band, so will save me a fortune day-day and should hold its value well too for the next year or two.
I think the critics should try driving one - especially with the S-Tronic (DSG) box, which is amazing. I never thought I'd ever buy an automatic before I tried it.
In pure driving terms, the TTS can't quite compete with a Porsche (I had a Boxster S before the 911 too), but I can assure readers it isn't all that far behind, and even leads in some areas, such as comfort, the interior and (in my view) overall build quality too.