I agree. I happen to use instant messengers a lot (both for work and personal use), and absolutely love the 'lightness' of the GTalk client. The quality of voice chats is of the highest order, and if you throw in the browser based chat feature, plus this new video chat, the entire gamut is very impressive.
It is one of the few applications for which one might like to become paid customer wholeheartedly.
One feature that doesn't show up on either the downloadable or the GMail system - only on the Flash one - is the ability to post URLs to YouTube, Flickr, and Picasa and have them automatically embedded in the chat window. I think it's an incredibly useful feature - similarly to how Facebook does that for posts - and I wish more IM clients began adding embed support.
It is one of the few applications for which one might like to become paid customer wholeheartedly.