Initial impression: the UI is very simple and spartan in the usual Google style. The feature list is pretty small so far, although VOIP is front and center. They seem to be very strongly focusing on being standards-compliant, and brag about working with a number of the common clients and a lot of different standards right off the bat.
Nothing terribly remarkable initially, but I suspect that this will be most important as the common entree into "Google on the Desktop". It already has a gmail notifier built in, and I'd be very surprised if they don't start adding other Google-related features fairly quickly. The notion of the "Google account" is becoming more powerful by the day -- they are adding a lot more features for people who give them an identity...
