Thanks for posting these pics and starting the thread Gok!
So I messed with this figure a bit last night and my first impressions are as follows:
First of all, yes he is a pricey MP but he is also massive, and I mean really massive! The deco and sculpt (especially in dino mode) is just absolutely gorgeous and dripping in detail, they really went to town with the aesthetic and I love it.
Before I got home to work out how to transform it, Gok and I had a lot of fun just messing with the dino mode at a cafe (as a NSW resident, this is the first Masterpiece Megatron I have legally been able to take out in public

). The dino mode has a pretty decent range of articulation, they even worked some movement into the tail and the mouth opens wider than you'd probably expect. Speaking of the dino mode, the only robot parts that are visible are the robot knees, otherwise everything else is very well hidden, and the robot knees are only noticeable if you really look for them. Overall they've done very well here!
The robot mode is very well articulated and represents the CGI cartoon faithfully, it looks great and balances quite well in various poses. Otherwise, there isn't much to say, it is great though.
Now for the bad. Please note I am only speaking for my own experience, so if you have had a better experience then I am happy for you.
The robot mode transformation was quite scary due to all the panels and tabs. I was so scared I would break it extending the waist hinge for the first time. Transforming the back kibble was also scary just due to the thinness of the plastic and how complicated it is to all fold away. Going back to dino mode I had some trouble getting everything to fit together, but overall it works. I don't want to scare anyone into not buying it, as nothing actually broke on mine, but just be careful is all. Now I understand this complicated transformation is necessary to make it as CGI faithful as possible, but the end result is a very delicate feeling Transformer, so just be mindful of it.
Overall I'd give him 8/10. He loses points for a scary transformation, but once he's in either mode he looks absolutely exquisite.