Well, I was fortunate enough to get a Google Wave invite last night, and I spent about 4 hours playing around with it.
Here are some initial thoughts. After "waving" with three people, what struck me the most was the sense of melding of communication. When in a "wave", you can see what the other person(s) is typing in real time, you can be typing at the same time, and you can enter into another one's comments as they are typing to address something that perhaps you find in the middle of their sentence.
That is an extremely interesting notion, one that will take a while for folks to become comfortable with. After waving for a bit, and because of this, I at least got a sense of fulfillment. I waved with three people that I had never met before, and the openness and willingness to share was something very "cool", maybe extraordinary.
I use the word extraordinary intentionally, because I believe a significant issue with using Google Wave will be the willingness of others to engage and collaborate with others. Thus overcoming this barrier could point the way to collaboration on an unprecedented level. That to me is very exciting.
One does have control over the tempo of each Wave. However, the norms around "how to Wave" are completing up in the air at current. I believe that establishing common norms around "netiquette" was a useful framework to better assist everyone in knowing proper and improper manners and actions of interaction for forums, discussion boards, and now found in text messaging. Some of that will obviously be carried over into Google Wave, but nothing more at current exists regarding Google Wave.
Why is this important? Because users are "playing" with Google Wave trying to determine what it is, and more importantly, what is it for. The most significant potential use, as I see for Google Wave, is collaboration. This then is why I see collaboration as a major issue. With Google Wave, people have the chance to collaborate at a pace and without barriers in ways that I have never seen or participated.
So at current, for me at the very very early stages of using Google Wave, is that it is a very open medium for communication and collaboration. I sense that many with Google Wave accounts really like it, but just do not know how, under what circumstances, and the what to expect when one engages with others in a Wave.