Anyway, my first impressions. It lags a bit. Quite a bit, with over ten people in a wave, especially a large wave. I expect it to get faster, as it's only a preview(aka beta) ATM. It's also annoying that anyone can edit other people's posts/msgs, once they've been invited. I expect that there will be a moderation option released soon, that lets the wave creator mod it, plus people he adds to the mod list.
Cool things were the gadgets, and seeing people's messages as they typed. As for usability, it's a step above traditional IMing. Not sure whether it can replace forums. Yet. But I can see it replacing IMing and email and blogging.
One thing I want to see is a nicer way to manage group projects. Perhaps i missed something, but there isn't an easy way to do the multiple-people-editing-a-file at once thing.
