Iridium built on the Chromium code base. This team took out all of the Googlely call home stuff and with the right privacy and security defaults set correctly, you have a really fast browser compatible with Chrome and the Chrome extension store. All of the plugins and apps work.
They kept the "sign-in" to sync your browser, but if you sign in with a Google account then you're defeating the purpose of getting away from Google's spying. I'm on multiple computers and don't sign in to sync on any of them. Export bookmarks, then import on another computer or browser. Passwords are sync from Lastpass or some other source.
DO NOT STORE PASSWORDS IN ANY BROWSER
On Linux updates are done automatically, but Iridium doesn't call home to check if there's an update. This is accomplished easily enough throug the menu. Iridium is completely Open Source and the code is available on GitHub in their repository.
Some audio and video codecs are not included, but normal browsing the major sites work fine. I haven't had any issues with audio or video. Flash isn't install, but Flash is outdated and a security risk. Most extensions and plugins work seamlessly.
An impressive list of Privacy enhancements - Too many to list here:
Differences between Iridium and Chromium
An excellent replacement for Chrome. Available for Windows, Mac and most Linux distros. No Mobile version is available.