Why would people need to have purchased the thing to critique said thing? There's no subjective trickery happening here. Out of the box, we can easily see it has loose knee joints. Hasbro fucked up. Meanwhile, youcan stand Unicron up and then turn him parallel to the floor and his legs would stay straight.
I was tempted on getting him but I'm glad I didn't jump on the chance. He can stand, sure, but you can't have him trying to step on someone or even be remotely dynamic.