Avengers: Infinity War is the movie 10 years in the making. The MCU (Marvel Cinematic Universe) as we know it started with Iron Man I in 2008. 10 years, 18 movies, and plenty of superheroes later, Avengers: Infinity War was just released.
Avengers 1 and 2 are a lot of fun and a lot of action. Avengers 3 (Infinity Wars) is still a blast to watch but it's much, much darker then it's predecessors or really anything else in the MCU. But that just makes it all the more interesting. And it shows how Marvel has really grown as a company. DC doesn't have a monopoloy on dark superhero movies anymore.
This movie is not for the casual Marvel viewer or for someone who just likes superhero movies. And it would be a terrible introduction to the world of Marvel movies. To truly appreciate Infinity War, you need to have watched every MCU movie at least once. I actually did an in order rewatch with a friend which was very helpful. If you're crunched for time, I would recommend seeing Avengers 1, Captain America 3, Black Panther, and Guardians of the Galaxy 1 at a bare minimum. But you should really see all of them to fully appreciate Infinity War.
So why do you need to see so many movies to fully understand this one? Well, this movie was being planned for ten years and every Iron Man movie, every Thor movie, every Avengers movie, they were all leading up to this. Seeing your favorite characters from different MCU trilogies interact with each other is amazing, but only if you know who they actually are from previous movies. With knowledge of the rest of the MCU, the highs of the movie feel higher and the lows feel lower, especially because so many plot points are connected to character development.
This movie is very dark for a Marvel movie but it also has a lot of funny lines. This film does a really solid job with pacing. They go from something heartwrenching to something that makes you laugh without missing a beat. And everyone expected this 76-character film to be a hot mess. They don't call it the most ambitious crossover of all time for nothing. But it really wasn't a mess. And the cinematography was fantastic.
Without going into specific detail, the characters were put into small groups so you could keep track of them. They did this instead of having each character in their own "world" and side characters were kept to a minimum. For example, I thought Tony would be hanging out at Stark Tower and the Hulk would be hanging out in a lab but they did not separate characters to that extent which definitely made the movie easier to watch.
Even though it's a superhero movie, I would not recommend bringing small children to this movie. It's fun, it's funny, and it's fast paced but it's also one of the darker action movies I've ever seen and definitely the darkest film in the MCU. Overall, everyone should go see it because it could have been a bit of a disaster but was truly a beautiful movie and truly a step forward for Marvel.