Just had a catastrophic failure on the one I bought for Christmas. The diecast folding joint that connects the torso to the waist at the back of the collapsing spine piece just completely split in half during transformation. I luckily can leave it in fighter mode, but yeah not happy. Gonna chalk it up to a fault in the metal as I've never seen this issue reported but be careful.
Guess I get to look for a new one to buy now. Yay.