This is probably the first beta release of a new version of Chrome in a long time, where everything works pretty much out of the bugs. Chrome 38 Beta is faster and it didn't break any plugin functionality or it didn't show any strange behavior on web pages.
Mac users of Chrome have a chance to work on the new 64-bit browser. Not all Macs support 64-bit programs, but if you have a newish computer, there's nothing to worry about.
The Chrome for Mac team says that their new browser will no longer support 32-bit NPAPI plugins, but their 64-bit counterparts are supported. In order to check if you are running the 64-bit of Chrome, just go into your Chrome Menu and tap on "About Google Chrome".
The new version of the browser brings, on the other hand, something less geeky and more user friendly. From the Chrome 38 beta you can use profiles to your browser. Switching a preference will take you to a menu that will let you change the profile from yours to a friend's. You can let your girlfriend type in her Google account password and she will be presented with her bookmarks and history.
There's also a guest mode where you can choose to let anyone play with your browser, and as soon as they close it everything will be nice and clean.