The new version of Google Desktop is a beautiful piece of software.
While the features are nice, it is the little things that make it a joy to use. For instance, the animation it uses when scrolling though the extended displays of mail messages or news items is the kind of thing one would have previouly expected from Apple.
The included aggregator is Google's best effort yet (better than www.google.com/ig, anyway – I don't have the GMail aggregator turned on), although I think I'll still be sticking with Bloglines (at least until Findory get its Feed Reader to import subscriptions).
One hint: if you think using it as a sidebar will take too much room set it to AutoHide. Then you get the benefits of both the sidebar and the extra space.