Hot Tub Time Machine 2 follows up a movie that was self-aware and surprisingly good, with a sequel that is mostly just dumb. John Cusack didn’t come back, so he’s replaced by Adam Driver, and with no Cusack there’s no need for Lizzy Caplan (and she might not have done it anyway), so Driver gets a love interest in Gillian Jacobs.
Likable as they all might be, the plot of the movie is weak and gives few opportunities for comedy. The first movie was structured to make references to 80s movies, let the characters take advantage of their future knowledge, and had some jokes like Crispin Glover losing his arm. In this one, they travel to the future, and… basically nothing funny happens there. There is a segment at the beginning showing what the characters are up to that’s funny, and a montage at the end of time travel hijinks that was pretty good, but the whole middle of the movie was a drag.