There has undoubtedly been a lot of hype on Google Wave in the blogosphere, and to be honest I believe most of that is noise arising due to the limited number of accounts available. It is still in preview, which gives it earlier than beta status, and it shows. I am certain that Google are working hard on the protocols and federation technology behind the system as for the moment the interface is a little clunky and takes some adjusting to. The plugin system is neat and allows for a lot of scalability and expandability within wave.
Its hard to know what to compare it to, its far removed from twitter/facebook micro-blogging model, if I had to choose I would compare it to a forum, where one can add any sort of content and gadgets. This is one of the oversights in wave also, I would have assumed waves to have been non-linear and being able to jump in at any point and edit/insert anywhere in the wave. The timeline concept used does not seem immediately useful but I guess some more time will have to pass to judge this fully
Drag and drop file upload is nice, tho embedding images could be handled a bit better. Things I would like to see are support for other Google services, like Docs and Calendar spring to mind immediately.
Wave has potential, but seems to have quite some way to go yet.