The change log includes:
- Material Design updates
- Simplified sign-in
- Lots of bug fixes and performance improvements!
A quick reminder that you're not going to see tabs separated into individual cards just yet, unless you're running the L developer preview.
If you are interested in getting in deep with all of the changes in the Chrome 37 beta, you can check out the SVN revision log with all of the details. Will you take a chance and download the newest beta version of Chrome for Android?
Source: Chrome Releases blog