Hype alone is usually enough to make me go "meh" and ignore something until it's part of the furniture. Something finally made me look at Flock though, and I'm glad I did.
Flickr integration alone means that if you're already a Firefox/Flickr user it's worth checking out the latest beta. I'm still working out how it interfaces with del.icio.us and multiple blogs, but it's found all my Blogger blogs already. If you're reading this then the blog editor works!
It seemed a little laggy in the interface, but I think that was whilst it was indexing my history in the background - it's better now. We'll see if I'm still with it in a week or two, but for now I'm using it as my primary browser. I even uninstalled Firefox... imagine!