Quick notes for now. More and photos to come.
Starters, his head is a big Improvement over CW OP. Ball jointed so it can look up and down as well as side to side, and seems more in proportion to the rest of his body in comparison to Optimus.
Quite a lot of pieces have been remoulded, obvious both his heads, but also the chest, parts of the cab front, cab rear doors, there's an airfoil now, new codpiece and combiner chest piece. Not quite a Springer/Sandstorm level of remould, but enough that the robot modes are different enough, even if they have the same silhouette.
His hip ratchets are a little smoother than OP's, which were quite stiff, so posing in both robot and combined mode is a fair bit easier. I like the combining sword/gun idea, means that his robot weapon is not too small for Menasor, and Menaor's is not too big for Motormaster.
Summary: While I like CW OP, Motormaster is definitely the better version of the mould.