Alright, I could go into a little more detail on why I don't like BTTF2 all that much ...

Whereas BTTF & BTTF3 are distinct movies with their own distinct stories and styles, BTTF2 is just a parasite that piggybacks off of BTTF in order to exist; it has no distinct story of its own -- it's basically just a rehash of the original movie shown from another POV -- and beyond serving as a bridge between the two other movies, it serves no real purpose.

I heard the original idea of BTTF2 was for Marty to end up travelling into 1967, and frankly, I wish they had gone that route; it would have been more interesting and new ground would have actually been covered.