In my house, to test it, I tried Gizmo to Gizmo on the ITT (versions 4 and 5) and I could never get video to work. I switched to googletalk and the video worked right off the bat (still in my house).

I initially tried using the Gizmo client (which I guess I wasn't clear about in my last post on this thread). Then I went through the process of figuring out the SIP info for each account and trying it that way. Again, nothing but voice.
With Gizmo, I got voice working fine, and in fact, got voice working really well... except I still couldn't enter my passcode into a bridge (it didn't hear the DTMF codes), so in that aspect, the ITT failed me, using gizmo or straight connecting to a SIP account (where are the DTMF tones once you have a connection???).

I still couldn't get the video to work until I went with googletalk to googletalk.

For voice, I gave up on the tablets because I couldn't enter the passcode on a bridge (which for me is a killer since every call is hosted on someone's bridge). For video, I was still hoping to get immediate family facetime, but now I have been stymied by the (remote) hotel's wireless which the ITT couldn't get on to (on my wife's end). I can't say it is the ITT's fault, but it hasn't made it look good when I tried to video conference with my wife for my mom to see earlier tonight. (It is worth noting that I first got interested in the ITTs so that my kids could video conference with my mom. I think she is scared off of the platform for life now, not that that took too much to scare her off of a complex gadget

In conclusion, It does work sometimes, but it isn't as straightforward as it might be. When it works, it is awfully convincing, but when you try to show it off and it doesn't work, it is still convincing, but in the other direction. *sigh*