Speed is a big selling point, and it really is fast. It varies between blazing fast and quite fast, even for pages with a lot of elements like LJ friends pages. And it really does start instantly and close down instantly. I don't know how much this is because it's freshly installed, but based on today it does look significantly faster than Firefox.
Chrome renders HTML sanely, which is of course the first requirement in a browser. Obviously nobody's coding "for" Chrome yet, and I haven't found one single site that breaks even though they were presumably tested for FF and IE. So that's pretty encouraging. It can cope with messy badly written sites (my test case is *spit* Myspace), and blocks popups effectively. The only problem I've run into is that it occasionally hangs on Java-based games, which is annoying, possibly to the point of outweighing the benefit that it loads them far speedier than traditional browsers. Its typography is prettier than FF but less pretty than Safari. The new feature I like best is that it lets you resize text entry boxes at will, and does so smoothly and fast.
I think it's probably easier to configure than Firefox, but it seems awkward because the options aren't quite where I expect them to be. I looked for manage bookmarks for ages, and it turns out you just drag and drop in the bookmark menu itself. The range of user configurable options is much smaller than FF, but I think that's a correct decision; there was nothing that was forced on me that I wanted to tweak, just a streamlined, intuitive UI. There's almost no right-click menu, which I find odd, but I think that's a matter of habit rather than an actual criticism.
For me the biggest downside is that the so-called Awesome Bar is not awesome. I know that most people these days don't remember URLs or even use bookmarks, just type search terms and rely on autocomplete plus Google. I'm not most people; I use kinaesthetic memory to find my bookmarks and even unsaved pages, and Chrome doesn't want to let me do that. The Awesome Bar guesses right about three quarters of the time, but I would rather go to the right URL consistently, than go the right URL instantly but unreliably. I hate the fact that it almost forces you to open a new tab if you want to jump between pages; once you leave the homepage, you're in a simplified window which doesn't have the bookmark folder or any link to the homepage (other than the new tab button). So if I've finished reading my friends page and want to go and look at a news site, say, I have to fiddle with guessing the URL in the Awesome Bar ™ or open a new tab so I can find my bookmarks folder, and then close the first tab. And in new windows generated by websites, you're really trapped, there's no back button, and opening links in new tabs doesn't work, and you can't really even resize sensibly.
The spell-checker seems to be a bit erratic, but that's a minor problem. I think the biggest disadvantage relative to Firefox is the absence of extensions and add-ons. I don't use Greasemonkey or Addblock myself, but if you do, you'll miss those. For me, it's the lack of the LJ toolbar and the web developer extension that make Chrome seem awkward.
Overall, Chrome is not enough better than Firefox to overcome the inertia of switching, but it's certainly not worse and has a couple of nice little innovations. If I were setting up an internet newbie, I'd probably install Chrome for them in preference to FF, but for myself, I'll stick with the familiar.