Beat Chapter 3. The biggest negative for the game so far is something which I think everyone noticed long ago from the very first trailers and gameplay footage - the environment is severely lacking in terms of interesting art design and there's no variety whatsoever. There is the city and there is the underground Cybertronian ship/tunnel stuff. That's about it. Everything is reused a ton and it definitely gets really boring to look at after a while.
But whatever budget and resources they saved on the environments, they seem to have made up for in the characters. The animations are top notch, the models are solid, and it's so much fun to fight named Decepticons who not only move and attack in unique ways, but feel so true to their characters. There's a lot of detail and care put into the movesets of the characters, not just for an action game, but as fanservice to Transformers fans.
As far as the non-standard gameplay parts of the game goes, it's a bit of hit and miss so far. I really liked the Galaga style Insecticon turret mission, especially how it has specific waves and bombs and stuff. Really cool. I'm super happy they had an expanded sequence available as a Challenge Mission too. The vehicle chasing stuff is a mixed bag. The first one with Megatron on Longhaul was pretty great and felt tightly designed. The subsequent ones with the Sentry Bot and later with Thundercracker feel more poorly planned and wasn't super fun to play. It was fun to beat Thundercracker up though! The top down 2.5D thing is just baffling. It changed almost nothing about the gameplay except the camera angle. It would have been pretty cool if they made it a full Ikari Warriors style thing instead with unlimited ammo for range attack, but as it is, I'm not sure what the point was lol. The sidescrolling 2.5D battle with Blitzwing was pretty rad though. The controls were kinda loose and it's clear the engine wasn't super suited for it, but I think it's one of Platinum's better rail-vehicle action sequences, lol.
The actual battle with Blitzwing was super solid. Great use of his Triple Changer nature to put a twist on things. I dream of a battle like that with Sixshot. One day.... hopefully...