My biggest overall problem with the stream was the chat server simply did not work and so I had no interaction with the people there other than texting Harry, I don't know if that was a problem for other people though. Other than that the stream itself worked well and it was a fun experience
The commentary...I may be a bit biased as personally I prefer no commentary at all (I doubt the option exists for the viewer to turn it off though!) but I thought the actual commentary, or that which I heard of it at least, was very well done and informative and Scott and Dave W in particular are masters of the art of explaining what is happening accurately and concisely. I do think the sound balance needs adjusting though - the volume during the FWS seemed to be a bit too weak so the background arena chatter was creeping in, and the audio should be balanced in favour of the commentary to make it a bit easier to follow if there is going to be commentary.
If the option were available to watch the matches without commentary and just the arena sound if the viewer wanted (is it possible to switch between audio feeds on ustream?) it would be perfect and I would be even more willing to pay, but as it is it's pretty good. Working chat though please ^^;