I liked the film quite a bit, but after stewing on it for a couple hours, I’m with the side that the original was better.
Problem 1: They went whole hog with the comic book universe for a lot of the secondary characters (Juggernaut, Shatterstar, etc.) and content, which clashed with the rest of the movie stylistically and really only served for some Rob Liefeld jokes that probably almost none of the audience could get and, even among those who do, are already so overdone and rote that it’s not really all that amusing at this point.
Problem 2: The style and tone of the film varied widely. The whole X-Force team get together - for example - felt less like a part of the movie we were watching and more like they shot it for the trailer as a joke and then decided to go ahead and wrap a small subplot around it just so they could throw it in to the movie. The quality of costumes and storytelling was notably lower than the rest of the film. It felt like they had different teams working on different subplots of the movie, in terms of everything from costuming to special effects, and edited it all together at the end.
Problem 3: They turned pretty much all of the characters into Deadpool acolytes. In the first film, only Deadpool understood that he was a Bugs Bunny style character, and everyone else was a fairly realistic person in a standard action film. When Deadpool did something awful in the first movie - cutting off his own hand or something - Colossus puked. In this one, he kills a few people sort of out of the blue, and Colossus is effectively like, “Aw gee, Deadpool. That’s so naughty. Teehee.” Negasonic is sort of annoyed by him more out of script expectation than because she really has a personality. Domino instantly and completely falls into line following him, without question of his leadership abilities, the worthiness of the mission, nor even caring much about his flaws as a human being. Cable tosses his wife and child away just to be besties.
Basically, the characters were deeper in the first film. Here, they’re all just cardboard cutouts and Deadpool went from being a half-serious character to full Loony Tunes.
Personally, while I think that’s all fine for one movie and there’s no need for the second to be exactly like the first, but rewatchability on this one is probably going to be way lower and I would doubt the continued success of the series if they continue towards full comic book and Loony Tunes style film making. Real characters and real situations, surrounding Deadpool, will provide a more solid structure for continued quality.