A colleague owns two and we used them on a gig a couple of weeks ago. He has updated to the latest firmware and that appears to have overcome some of the early problems, but you have to get your head around the way that they work - and that is not particularly intuitive.
In the end we used 3 CF cards for each camera, recording a live event. Changing cards out is not an easy process and so some of the material still had to be taken from the tapes we were running as back-up (SD mini-DV).
The quality of the final result is fine, but I would not recommend them for this kind of live-show environment where you have to make fiddly adjustments to get the cards in and out while trying to maintain a picture. For other, more controlled environments, I think they are a reasonable product that will probably need to undergo a few more firmware upgrades to shake out the little oddities. For the price, they're a good investment to tease some more hours from a perfectly good camera that has a tired tape-drive.