So Decapitron is from the Puppet Master horror movies. His name isn't a reference to him decapitating people, it's a reference to his ability to swap out his heads. All the Puppets in the Puppet Master movies have the soul of a person the Puppet Master originally knew, and Decapitron, introduced in Puppet Master 4, is one of the most powerful because it houses the soul of Andre Toulon, the creator of the puppets.
Decapitron comes with three heads, because that's what he had in the movies. In the package he's got the head of the Puppet Master himself, Andre Toulon. The other heads are a robot head that allows Decapitron to shoot electric bolts at people and a blank "off-mode" head. I think. I only saw 20 minutes of Puppet Master 4.
The first thing I checked on Decapitron was the joints. Cut joint wrists were the first disappointment. The Cut neck joint was kind of disappointing too, but more common on this scale. Although once I began to play with the interchangable heads, the cut neck made sense. At first I thought the shoulder joints were cut joints, but after playing with it for a second I realized that it was actually the jacket restricting the joint movement. A little rejiggering revealed a more typical ball joint.
As for the interchangable heads. Unlike other 1:6 scale heads, where you're meant to pull them of a peg, these ones have a weird tab system. Well, look.
Oh, and incidentally, this is one of the smaller 1:6 scale figures out there. Here's what it looks like compared to a sideshow clone trooper.