Adwords Editor is a great tool for anyone spending more than an hour on PPC every day. The latest version makes it even easier to manage multiple accounts. Some of the features that I found great time savers:
I believe at this stage Editor has most of the features as in the web interface. The only few minors things missing are the Impression share stats (for some reason they are not included). Maybe in the feature the ability to link Google Analytics with Editor (it would be great to be able to see bounce rate/page views).