Here is the first look at Sentinel Prime in his Firetruck vehicle form and robot form.
Megatron's offical images
The Ark as well.
Lastly a look at the Ultra Class Optimus Prime with trailer that combines to give him his jetpack.
I think that Sentinel Prime looks pretty sweet. Optimus Prime on the other hand looks like a downgrade of the ROTF Optimus Prime toy. The arms look to bulky and his wheels should not be on his arms.
What do you guys think?