Basically you can read on their page about "super power; super low energy cost" devices you won't probably ever see
BFL is in "shipping in two weeks" status since last summer if i am not mistaken - so far noone really recieved his devices. BFL has raised an incredible wealth during preorder and almost every two weeks they bring us a new informative message e.g. "we encountered unexpected problems, but we will surely send our products during next two weeks".
On the other hand they delivered some FPGA in the past, but it was imo more than year ago. So they might not be scammers, but real hardware developers thats started bigger project than they can effectively handle.
If i can get you an advice - don't buy anything from them. Even if they deliver products eventually, you have much better ways to invest your bitcoins untill that time (be sure majority of preorders won't be delivered until end of years - if any will be delivered at all)