You gotta remember nVidia were going for a MultiFunction GPU with these cards. ATi went for plain rendering power in currently used paths - nVidia were planning for the future and a more general purpose for the 4** series cards.
I like the PhysX acceleration a lot - It makes a big speed increase in some games, and I'm currently re-playing through GTA4 and then the 2 episodes; the nVidia cards walk through these games and others I'm playing; in all honestly when you're at the level of ANY of these cards (ATi or nVidia) then the extra 10% raw performance in DX9 games means nothing really. Difference between 200+ fps in a Source engined game or 210+ fps = I can't say I notice the difference
I also like the implementations of CUDA I've used so far and the Adobe acceleration etc.
If you read an actual description of the hardware you'll see that nVidia had something far greater in mind than just DX9 and 10 fps for these cards; and in actual fact, hot off the press (today or yesterday I think) = ATi announcing that their next cards to come out will follow a similiar engineering "think" to nVidia's... (tesselation included). By that time nVidia will be on their second generation of this type of multi-path (G)processor.
Having experienced a 5870 running at full whack 24hours a day for almost 2 months, and having used the 480, there's not much difference in volume...
Oh yeah did I mention that I like NOT having screen corruption in Windows because I use Win7 64bit and a dual monitor setup? LOL