The service is a weird hybrid of email and instant messaging but doesn't suffer for being neither one nor the other. Indeed, it'll benefit from it hugely. It can be used like email for occasional dippers-in, or like a constantly-updated collaborative tool for those who are online all day.
Indeed Wave could seriously reduce the amount of emails back and forth between colleagues working on the same business project. Google predicts that business will want to deploy their own internal versions of Wave on company servers for this very purpose.
One of the strangest things about messages within Wave is that you can see instantly, letter-by-letter, what fellow collaborators are typing into a Wave (though there is a draft mode) and different people can edit a Wave at the same time, just as in Google Docs. Most amusingly, this means your buddies can see what an abysmal typist you are.
You can also playback waves so you can see how conversations have evolved – including what time messages were added and edits were made (yes, you can edit anything but this is logged).
There's also a mobile version of the app but this is extremely limited in functionality at the moment (though it does show your Inbox and contacts in a clean and simple interface).
At the moment using Google Wave is a bit like being a football scout. But one that has to get up at 8am on a Sunday to go and watch an Under 12's football match in driving rain. It's far too early, the conditions are uncertain and you're asking yourself exactly what you're doing there. But the potential for greatness is present.
One friend noted at the end of our conversation on Wave: "See you on Twitter then." But the key comment was in his previous sentence. "What's it for? But to be fair, I asked the same about Facebook when I first logged in."