Aside from being offended by say the film's treatment of female characters or violence, another problem I could see someone having with Kick-Ass 2, is that it simply retreads ground covered in the first one under the pretense of the story and characters advancing. I'll forego a discussion about the film's themes and content mainly because it's (1) certainly a discussion that a person much smarter and informed than I should even broach and (2) similar to how I approached the first, I'd rather focus on just the basics of the filmmaking approach especially considering this is a sequel during another summer of sequels (or prequels, threequels, remakes, reboots, etc.).
Jeff Wadlow certainly doesn't have as careful of a directorial hand as Matthew Vaughn displayed in the first where at least the characters had a few moments to pop and surprise me. Instead we have just a few action sequences and gimmicks that are entertaining enough for someone such as myself who enjoys the escapist, horrid, and ludricous work of Kick-Ass's creator, comic book writer Mark Millar, as a guilty pleasure. Therefore, Kick-Ass 2 feels like a pale imitation of the first. Dave Lizewski (Aaron Johnson) was a comic book nerd who decided to try out being a superhero in real life in the first film. In the second film, Dave wants to just act as a neighborhood watch. Mindy Macready (Chloe Moretz) was an eleven year old girl who is trained to be a fierce killer that swears like a sailor in the first film. In the second film, Mindy is stuck trying to join a 'Mean Girls' clique and is forced to hang up her costume. Frankly, both the characters don't really advance all that much. My favorite sequels are the ones that take everything about the first film to the next and often deeper level (a classic example being the Ripley character's development in Scott's Alien to Cameron's Aliens, both great films made in a different in style).
The first film also had a very surprising and inspired performance by Nicolas Cage as something along the lines of Adam West's Batman meets a psychopath. It seems like the filmmakers were hoping to capture that same magic with the casting of Jim Carrey as Colonel Stars and Stripes, but the performance, although inspired, is nowhere near as out-there as Cage's and it feels quite limited due to the character's eventual fate. With the personas feeling less developed, Kick-Ass 2 feels like less of a satire and more of a blockbuster as opposed to the first which at least made an attempt (to varying degrees of success) to walk that thin line. I still laughed quite a bit and some of the scenes were exciting and fun to behold from a visual standpoint, but I was hoping for more. Afterall, the subtitle of the comic was "Balls to the Walls" for a reason. Seems like the film forgot that in the translation.