On linux its a little unstable (the latest update seems to have broken gmail, of all things), but amidst the upgrades there are some nice new features included from time to time. The latest one I've noticed is that the bookmark bar only appears on empty pages, saving screen real estate on pages in-use. Sweet!
I'll also mention that I'm very excited about the new Google operating system: "Chromium OS". I'll leave it at that as I wrote up most of my thoughts about Chromium OS at the Soggy Blogger. Read 'em there if you are interested!