The first thing you notice when you open them is that these are marketed as keychains, but they're really not. There are key rings included, but they're attached to the minimates by a thin string around the neck which isn't looped or tied with a not. They're relying on the permanence of a neck joint in a toy designed to have the head come off. Oh and the string can be removed without taking the head off I you're trying hard enough. So I'm expecting some kid is going to lose their minimate if they do something like attach it to a bag zipper. I'm going to assume this whole keychain thing is a workaround so that Diamond can license toys in this scale.
The toys themselves are nicer than I anticipated. I was afraid the Turtles would end up as glorified Battle Beast minimates with extra parts slipping over the minimate base humanoid body. But these are more sophisticated, with the animal body parts and ninja padding sculpted onto the body base. This means the feet aren't removable, but that's a small price to pay for slightly more stability in the figure.
Interestingly, Michelangelo's nunchucks are connected with metal chains.
Oh and all the turtles have weapon holders sculpted onto their shells. And really the heads and shells are the unique bits since aside from color, the turtle bodies are identical, but they're minimates so you have to expect stuff like that. And I like that the figure stands for the turtles are sewer lids.
The human/robot figures that come with the figures are serviceable. The four arms of the robot foot soldier is pretty cool, and Shredder has a scarred face under his mask, but I'm not getting these figures for the humans.