Anyway, along with this other person, I started checking out all of those features promised in the intro video. Many features aren't implemented yet, which makes the experience very incomplete. Most importantly, I was hoping to publish this post from Google Wave, but the plug-in simply does nothing.
After a few hours of blipping, we got this one giant wave, which is very much not readable, and there's no way of understanding what's going on within. The fact you can post replies in the middle and anywhere else makes it very difficult to follow. Also, you must use keyboard shortcuts if you really want an uncrippled experience.
Finally, I can say that while I am excited to be part of this beta, I think this platform isn't revolutionary. It's a nicer way to have email (like GMail interface is better than Outlook), and an awful way to do IM. Perhaps when the plugins would work it'll be better.