Mark Harrison’s review published on Letterboxd :
Watching in 2017, I got chills at the blackboard part, where Doc explains that they can't just travel forward from alt-1985 to stop Old!Biff going back in time, because they will be the future of that darkest timeline. Heck, maybe alt-Biff would be Presi-- OH GOD, WE'RE THERE, AREN'T WE? THAT'S OUR TIMELINE.
Part II is messier but just as rewarding as the first film in its progress from setup to payoff, echoing many of the bits you loved last time and yet somehow never feeling like a rehash. It's definitely more of a special effects showcase, but it's a perfectly charming middle chapter for the most part, particularly in any scene where Thomas F. Wilson gets to play the same asshole twice, interacting with each other from different ends of his life.
And Great Scott, I entirely forgot how much I loved the ending. 1955!Doc reacting to Marty immediately coming "back from the future" makes me laugh every time.