Pro Actively supported by Google
Chromium was first released as a large portion of Chrome's source code as an open source project by Google in september 2008. The idea was to encourage developers to review the underlying code and to contribute in making Chrome cross platform and port it to Mac and Linux as well.
Nowadays Chromium is a large project with a huge community that's standing behind it but still Google continues to take an extremely active role in Chromium development. This ensures the longevity and constant development and improvement of the browser.
Pro Supports all of Google Chrome features
As Chrome is based on Chromium they overlap in supported features. Chromium syncs between devices, automatically updates, has great built-in developer tools, installs extensions without a restart, includes a combined text bar for entering URLs and searching and has excellent HTML5 compatibility just like Chrome.