Funny how so many people are concerned about privacy, and yet go on uploading their entire life to Google's servers. Concerned about the information your government is collecting about you? Haha. You should be as concerned (or more concerned!) about what Google is collecting about you...
Google Wave is really slow now, it's buggy, and needs a lot of work to get to the beta stage. It's too early to judge, but it possesses some really unique and powerful features.
It should be better than email. Unfortunately I think it's IM capabilities are just too powerful for it's own good. Very, very quickly you end up not know where to look.
I think it's much better than email. I would rather everyone used wave instead of normal. It sold itself as an email replacement so I think on it's criteria is a good tool.