i did one dive with it, so this is not a full review, just some initial thoughts.
i was not diving with a camera 
here are a few of my impressions:
- when swimming horizontal, breathing is easy; though initially a bitstrange to have the sound of bubbles come out from behind you
- when you look up or go to a more vertical position, air starts flowing easier ending in close to free flow should you put yourself on your back
- when heading down, breathing gets more difficult and you have to work harder to get air
so positioning of the combined 1st 2nd stage wrt to your lungs is goign to be key to get a good breath of air in most positions.
aside from that, i found the mouth piece uncomfortable and the 2 tubes restricted head movement sideways, they also tend to float up and pull on your mouth, but i am sure that rebreather divers will have a fix for that.
it was such that i did not want to try it again, though i am sure that i could get used to most of the downsides i have listed here
so in my opinion, it's more of a gadget than anything else, but that's just me. if you really don't want the bubbles go with a rebreather, closed or semi closed.
eric was trying one out in bonaire so i am sure he will have a lot more to say when he gets back. i'd be interested to hear that
hth
/paul