Obviously the biggest problem with this model is that it's not purple. The second biggest problem with it is that it's orange and grey, but that's pretty minor compared to the fact that I can't buy swarms of purple USSAL crabs.
This is my favorite design in the entire Masterbuilder set. Like everything with an exo-skeleton on MATA NUI Island, it's missing a pair of legs, but that seems to lend a certain comical look to them. The posable eyestalks allow the crab to be rather expressive, especially compared to the other fourteen animals in this set.
The arms can be pulled back by squeezing the the T-connectors on the top of the hinge points, and will snap forward to attack anything directly in front of the USSAL (prime attacking range to go after a NUI-JAGA). My one real problem with this design is that the rubber-bands are way too loose, so the claw arms barely pack any punch.