I was struggling to think of why I'd ever need tabbed Finder, but I can come up with a couple use cases. The majority of my Finder usage would be un-tabbed, however, and rightly so.
Pausing background apps, also hard to fathom, but as long as it's developer-decided, so be it. Multiple monitor support hopefully means multiple menu bars and docks as well.
I am slowly coming around to 10.8. 10.7 remains a travesty, and 90% of my computer usage is still on 10.6, but I'm coming around to 10.8. Hopefully whatever 10.9 is like, it fixes most or all of the things that still bother me about the direction of OS X.
What I'm really looking forward to is rumors of OS 11. I think that's where you'll see Ive's true influence. I believe it's the reason for Apple's management reshuffling, as well. I'm hoping Apple maintains good backwards compatibility with OS X, while at the same time building from the ground up with a modern set of decisions. We've come a long way from 10.0 and OS X is showing its age. The way we interact with computers now is so much different. I don't want to see OS 11 go more towards iOS, but have it be a reaffirmation of what makes full-featured personal computers useful. At the same time, it can fit better in the cloud and work with our other sorts of devices better. I'm thinking a new filesystem, similar but better interface, and some real bottom-up improvements across the board. So many of the problems with OS X is related to its original design constraints, with features glued on top of an aging kernel. I really can't wait to see what Ive and company create when they're freed from those historical restrictions. OS X "2.0" could be really very exciting. Oh yeah, and dump the stupid cat names.