The latest version of Chrome includes fixes for thirty-six security vulnerabilities.
There are numerous other changes in Chrome 57.0.2987.98. Google didn’t see fit to highlight any of them in the release announcement, so you’ll have to read the browser-annihilating change log to see if any of the changes are of interest. I’m not planning to do that myself, as it’s likely to take several hours, and unlikely to be particularly rewarding.
Chrome updates itself on its own mysterious schedule, but you can usually trigger an update by going to its ‘About’ page. Because this version includes security updates, you should try to update Chrome as soon as possible.
Update 2017Mar16: Ars Technica points out that Chrome 57 includes power saving features that should extend battery life for Chrome users on laptops.