I really hope they treat this as a sequel and not more episodes of the same gameplay. The cartoon graphics have to go. I would like a little more free roam exploration and maybe some platforming not just an adventure point and click. In fact that's my major problem with BTTFTG. I hate adventure games. Good on story but weak on gameplay. There needs to be some more action involved. I would love for some uncharted like platforming while keeping some of the point and click/puzzle mechanics.
Also is it just me or does Marty not seem like Marty anymore? He seems like a kid not a teenager.