They're really nice units. At the time they were first introduced to the hobby they were claimed to beat Tunzes in cost but in the end that's not really the case. But they are pretty slick units. For one there is no electrical part in the water. And with the controller they can create some serious flow patterns. There were demo videos from about a year ago, here check out this one from melevsreef,
http://www.reefcast.com/episodes/reefcast15.mpg
The only real drawback to me that I see, it has to sit square on the glass so that limits your placement options and you can't rotate it to be at an angle to the glass like you can with a Tunze.
Otherwise though they are pretty darn slick little units!