To summarize briefly, TokBox is an Adobe Flash-based video chat application, which runs in a web browser. This was pretty interesting, because it didn't require any additional software download or installation (other than what happened "automatically" in the browser), so it was quick and simple to use, and you could arrange for anyone else to call you, regardless of whether they were a registered TokBox user, by simply mailing them a URL to your TokBox address as long as you were logged in. The only other video chat program that I know of which has this kind of functionality is SightSpeed, with their "SightSpeed Light" client.
Because I considered TokBox to be a "quick and easy" video client, I didn't concern myself much with the amount of stuff that was missing compared to the other major video IM programs.
Now, with the Adobe Air based client, you don't have to use a browser to log in to TokBox, and once you are logged in you can leave it running in the system tray, so you are always ready to make or receive a call, without the bother and confusion of having a browser window hanging around all the time. That is a good thing, for convenience and usability, but in my opinion it moves them into a different "league", where the standards are higher, the competition is tougher, and things are generally more interesting. At the moment TokBox doesn't stand up to well to the competition overall, they come up short in support for different webcams (they are by definition limited to cameras supported by Flash), PSTN/POTS dial in/out, text chat (they have it, but it is very rudimentary), file transfer, and with the exception of Skype (which is still stuck on one-to-one video), multi-way video chat.
Also, and perhaps the biggest problem of all, it appears to me that their video data does not flow directly peer-to-peer, it goes through a server somewhere. I base this on my standard test, which is to make a call between my two laptops here in the office, and watch the traffic on the ethernet hub. When I do that with TokBox, I see the line to the gateway (and thus the internet) flashing along with the lines to both laptops; when I do it with SightSpeed, ooVoo or Skype, once the video connection is established the internet line goes quiet, and the two laptops talk directly to each other.
Don't get me wrong, I still like TokBox a lot, as a quick and easy video chat client. I love the fact that it is browser/flash based, and thus I can run it on my Linux systems as well as Windows. In fact, for the test that I mentioned above, one laptop was running Ubuntu, and the other was running XP Pro.
I hope TokBox does well, and I'm sure that their presence will put some additional pressure on the "big players" in this area.