They're all awful. They make no effort to hide the cheating involved. Optimus has parts of his vehicle mode transform into, and out of completely different parts of his body depending on which mode you're changing to. Breakdown's wheels just pop off and float when he transforms.
Yeah, a lot of them are not so good. Worst is Ironhide. You can see his legs pop out below his vehicle form (With the tires) while the tires that are supposed to be the tires on his legs are still there. So he suddenly gets 6 tires and then loses 2. DOTM ones are worse, though. Especially Warpath.
They did a good job on Barricade's and Jazz's also.. you can see where the parts go.. Sideswipe's isnt bad either. Warpath just drops backwards which makes sense, his treads are clearly on his back and legs so.. The worst one in my opinion is Ironhide :-/ everyone else is pretty legit.
Now that I think about it, I think the worst transformation sequences were in G1... and the best were the Bay movies just because you saw each part move into place from robot to vehicle and vehicle to robot, they put much detail in it which was cool to look at.
