I've been really excited about Google Wave and finally had the chance to give it a try today. There are some interesting ideas, but it seems highly unintuitive in surprising ways that I can't tell will become familiar over time. The first impression it left me with is that it'd be hard for Google to make this popular without some pretty big shifts in their approach. It seems enough like chat/email/message boards/comments to be familiar, and clunkier or confusing than any of them to be worth the time. Treat it like email or a message board, and get frustrated with how it organizes conversation. Treat it like chat, and get frustrated with the awkward interface and rapidly fragmenting conversation.
I find myself wanting to write up a bunch of suggestions, but only if I find a good chunk of time.