I got him and it's a mixed bag of good and bad in my opinion.
On the positive side, his alt mode is pretty rockin'. It's tight, has interesting transformation aspects, and seems to keep its own scale. The thing feels solid, when and if you lock it all down.
Little things like this annoy the hell out of me:
See that part hanging down from the bumper? That's his foot...it's just crammed back there.
Another thing I have issue with is the color of the red plastic. This seems to be a Hasbro thing, but what the hell? Is fire engine red copyrighted or unavailable for appearances on fire trucks?
His robot mode is good, if not a little spindly. It has good presence with the cape and the stylized legs. With little effort you can get some interesting poses and the mechtech shield is A-ok.
But see this shoulder joint?
better hope you get a good one because a lot of that articulation rests on a little black clip holding firm.
Last little thing, you see in this pic how high Sentinel's torso sits compared to Prime's? That's not the toy's fault but it might be one of the things that makes me a little harsh on the design of the character:
Overall, this is one of the top three movie leader figures. Optimus Prime and Starscream tie for spot number one and Sentinel is an easy third. He's like a cross between leader Optimus and Megatron, or if you get hung up on getting the arms in vehicle mode, a cross between Optimus and Brawl.