These are what we call the 'YMMV items.' Things that some people find in this work. We call them 'your mileage might vary' because not everyone sees these things in the same way. This starts discussions in the trope lists, a thing we don't want. Please use the discussion page if you'd like to discuss any of these items.
Alternative Character Interpretation: While Brainard himself seems to believe otherwise, it isn't too much of a leap to wonder if he might have a genuine undiagnosed memory disorder, especially considering the early scene where he's clearly having trouble recalling that he's even engaged, and that the rehearsal was the previous night.
Designated Hero: Professor Brainard is supposed to be "comically" absent-minded, but just comes off as a self-centered jerk.
Esoteric Happy Ending: The ending with Braniard attending wedding #4 from his lab by video proxy was supposed to be a cute, fitting end to the movie. Didn't quite work for many people.
Informed Wrongness: Despite the fact that Phillip has just blown off a third wedding ceremony due to his absent-mindedness, the movie attempts to make it look like Dr. Reynolds' Tranquil Fury response - and subsequent breaking things off - to his half apology/half "But look at this cool thing I made" exhibition was an emotional overreaction.
Mis-blamed: Some of the particularly obnoxious plot elements, including abandoning Sara at the altar over and over, are carried over unaltered from the original film. Of course, one could still criticize this film for not fixing them in the first place.
Squick: The subplot with Weebo's lust for the professor, progressing into creating a sexy female hologram so she can act out her emotions for him physically when he's asleep, and finally the admission at the end of the film that upon her death, she gave Brainard a copy of her design called "our daughter" - with modifications based on both Weebo and him. In case the analogy hasn't bludgeoned you hard enough, Weebo's final thought that allows Brainard to find the file? The word stork.