.... OK so I opened my mini MP Prime, and he is about as wicked cool as expected.
I love the size, he fits in great with the Classic-verse autobots.
The transform is the same as MP prime, and works well.
I think the cab actually looks a little better, the "point" of the chest is less pronounced, so he looks more like a truck (check the galleries of MP Prime to see what I mean)
He is a "little" flimsier than the full scale MP, but that is to be expected. He has no metal and all the fiddly bits of the original. It is in no way weak or fragile feeling, it just does not have the heft of the original.
The extra head is much cooler in person than it looked on camera. However, it does not appear to be able to transform due to the angle of the "ears". I didn't want to force it.
I was sad that it was not really possible to pose it in truck mode with the G3 trailer

No one said it would work, but I was hoping. The scale is very good between them, but the deck of the truck is too high for the G3 trailer.
All in all I'm very, very happy to have this in my collection.
I love my MP Prime, but I am very likely to disassemble my alt/MP display and use the room to expand my Classics, which are getting pretty cramped.