I have to say, the lack of top menus (file, edit, etc) was freaking me out at first, and it still feels kinda 'naked', but...I guess everything I ever needed up there is catered for elsewhere. Can't think of anything I use commonly that's missing. I'd prefer a status bar to see where links are taking me, I don't like the fadey blue bar.
Not 100% sure how I feel about the firefox3-Awesome-Bar clone, in my experience the awesomebar is barely any more use than the old address bar, and I doubt the google chrome 'omnibar' is ever going change the way I browse or save me any time. Also, not sure about the homepage - although it might grow on me eventually, it's a bit rubbish at the moment cos my site usage history isn't balanced out enough, and it feels cumbersome compared to my finely-tuned iGoogle page
It is pretty fast, faster than my (rather plugin-bloated) Firefox installation but not by much, it feels. That said, I've yet to properly try it out on an intensive JS-based web-app, which is where it would, it seems, really shine.
I don't see any infrastructure yet for plugins (unless they're somehow going to be handled by Google gears, which would be odd & hard) and I don't like the idea of a plugin-free browser, that's what makes Firefox extra-special; the huge library of excellent plugins.
The biggest problem so far, in my opinion? no f'ing middle mouse drag-scroll. Like Safari for Windows, I can't click my middle-mouse button down and 'cruise' up & down a page. It's annoying my tits off. In fact, even normal mouse-wheel scrolling in unresponsive and jerky...I try and scroll and it often does nothing for a few seconds. Early bug, I'm sure, but irritating enough to stop it being my day-to-day browser.