Chrome is a web browser developed by Google and distributed free. It has been criticized for sending usage data back to Google. Open source code has been released. The offending parts of Chrome have been stripped out, and the resulting package dubbed 'Chromium'. This is now available in the Ubuntu repos. I don't know availability for other distros, or for Windows or Mac.
I have been using Chromium as my usual web browser for the past month. Here are my thoughts on it.
1. Chrome loads faster than Firefox, 4 seconds vs. Firefox's 20 seconds on initial load, and 10 seconds on subsequent loads.
2. Pages really do load and render faster than in Firefox. Not only did I notice this the first day I used Chromium, but after I had been using Chromium for a week and returned to Firefox, FF felt distinctly sluggish. (I tried FF again because a website wasn't working right and I thought it might be a browser issue; it wasn't.)
3. Chromium remembers some passwords that Firefox always forgets.
4. If a URL is present as non-link text on a page, once selected, the right click menu has an option to open it in a new tab. Firefox requires an add-on to do this.
5. Adblock and New Tab Redirect are available as extensions.
6. Viewing a page with styles turned off (occasionally necessary when the CSS coder has made really bad design decisions, like purple text on black background) is possible, but requires the Web Developer extension, which has been ported from Firefox. It can do many other tricks as well.
7. Start typing the name of the website you want into the address bar. As soon as the right URL shows up at the top of the drop-down list, hit enter, and Chromium takes you there. With Firefox you have manually move the cursor down before hitting enter. It's a little thing, but it makes life just a bit simpler and faster.
8. Many keyboard shortcuts familar to FireFox users are also present in Chromium. For example, to duplicate a tab, putting the cursor in the address bar and hitting Alt-Enter works in Chromium. 'Duplicate' is also a tab right-click options, which Firefox lacks.
9. Another nice feature, also not present in native Firefox, is the option to 'Close other tabs to the right' when right-clicking on a tab.
1. Bookmarks folder always takes 4 seconds to open! This is the most annoying misfeature I have found in Chromium. On Chrome webboards others have complained about this as well. Even when the user has just opened it, not changed it, and all data should be in RAM cache, opening bookmarks still takes 4 seconds.
Update, 10/7/10: I have found that slow bookmark display was due in part to my own error. My bookmarks file was bloated, after I had imported Firefox bookmarks three times, resulting in a bookmarks file three times as large as it needed to be. After deleting the extra bookmarks, bookmarks take about 1.5 seconds to come up. However: that is still slower than Firefox, which displays a bookmark file the same size almost instantaneously. And it means that as your bookmarks grow, your load times will increase. If this doesn't happen in Firefox, it still means Chromium is handling bookmarks in a poorly optimized fashion and could do better.
2. No option to start searching page as the user starts typing. User always has to hit F3 or Ctrl-F. This is the opposite of (5) above. It forces the user to make extra keystrokes. Chrome users have complained about this as well, to the sneers of Chrome superusers. I was shocked.
3. No DownThemAll, and the DTA team has no plans for a Chrome version. No FlashGot.
4. I have yet to figure out how to use Tor with Chromium. I think it's possible, but there's no Torbutton yet, and it looks like the user has to manually edit proxy configuration.
5. No way to turn off annoying animated gifs. Esc doesn't work.
6. Limited customizability. There's no about:config page, and many standard Firefox options don't exist. Example: if you load a large number of URLs from a bookmark folder simultaneously, Chromium will pause with a question screen: "Are you sure you want to open NN tabs?" Firefox gives you the option to check a box that says 'Never ask me this again'. Chromium doesn't, and you have to click the 'Yes' button in the question box single every damned time.
7. Ubuntu only: Tahoma font replacement intended for use only by Wine is used whenever a webpage specifies Tahoma. It's ugly, and in small sizes, nearly unreadable. (And there's one well-known RC vendor who does this.) Workaround: remove this font from system.
8. Addendum, 9/22/10: Hushmail java applet does not work under Chromium, even though the Sun site reports that java is working, and Hushmail java works fine under Firefox.
Overall: The advantage in speed outweighs the annoyances. After a month of using Chromium, I'm a fan, and I'll continue to use it as my default browser. But I'm on Linux. If you're on Windows, you might come to a different conclusion. Firefox development and optimizations seem to be aimed at Windows users, who probably outnumber Linux users by a hundred to one. I have no doubt that Firefox is friskier on Windows.