I'm a fan of the show. I don't think that its as great as everyone says it is, its a bit cheesy and stupid at times, but overall its well written and animated. I have a lot of fun watching it. That being said, this movie is a high-budget arc of the show. It fits in with the show, while remaining a self-contained story.
Overall, the plot is fairly straightforward with some twists and turns. There are a few annoying moments where they add in some flashbacks from early episodes of the show so that people who haven't seen the show knows what's going on. It slows down the beginning a bit, but at least it doesn't take up too much time, and is ultimately beneficial for the audience. There isn't too much unnecessary fan service, but most of the main characters that are on the island are only on the island so that fans wouldn't be upset that their favorite character wasn't in the movie. I didn't really mind it too much, as most of the scenes where they show irrelevant characters were still fun and entertaining. The ridiculous coincidences did have some of the audience laughing and yelling out in annoyance. Honestly some of it was more ironically funny, but at least everyone was entertained.
I saw this movie in a theater, and unfortunately that meant I had to watch the English dub. I've never saw the English dub of BNHA before now, and I'm sad to report that it is terrible. The only voice actors that were good were for Bakugo, the villain, and maybe one or two other characters. Some scenes weren't as impactful for me because I was laughing at the bad acting, but the writing and everything else was still pretty great. Also the sound design was perfect.
The animation in this movie was amazing. There is some cg in some of the fight scenes, and it looks great. The amount of effort that went into animating every frame is impressive. While there are one or two annoying wide angles where the characters had no faces, there are no frozen images in this movie. Everything moves. Also, there are several complex moving shots that look like they weren't aided by cg and it looks great. Also also, in every scene whenever characters are moving, ALL OF THEIR HAIR MOVES NATURALLY WITH THEM AND ITS NOT CG AND IT LOOKS AMAZING. Watching this on the big screen was definitely a treat.
Overall, I would recommend this movie even if you don't like the show. Its a fun action/thriller/comedy. While not particularly clever, and featuring some annoying tropes like "I'm not telling you why something is happening to protect you" overall its really funny (especially when you view everything it does wrong as a joke) its pretty good.
