The user interface has improved a bit, especially for exporting/importing bookmarks. Google has even added a search box to find settings, which can now be directly accessed via a web address – this is good if you’re helping someone remotely: copy/paste the address to an option and your correspondent should go exactly where you need them to.
Security-wise, Google has also “sandboxed” (or put in a compartment) the code that is executed by the integrated Flash player. This adds an extra layer of protection from malicious Flash objects. All in all, this should be an easy upgrade.