It looks like just a mini-chainsaw, with a jaw added to push the twigs against the chain. Nothing complicated enough to be too likely to cause real problems.
Electric chain saws have been around for long enough that BD ought to be able to make one that's reliable, but the professional tree workers don't seem to use them much. The gas chainsaws seem less likely to stall out when the chain jams in a crack.
A problem with a plain-ol' chainsaws with very small stuff is that a limber branch just pushes away from the chain instead of cutting, so you end up chasing the tree with your saw. (And there's often some "snap-back" when you break through.) This one would solve that problem for pruning small limbs, perhaps; but I wouldn't see much value unless you've got a lot of small limbs to prune. It would take me a lot longer to unroll the extension cord to run this thing than it would to cut a half-dozen limbs with a hand saw.
Since it's cute - in a manly(?) sort of way, I'd guess they'll sell a lot of them. I don't think I'll order one right away.