First of all, the MCU has grown into something huge with several timelines, universes and characters all combined into 24 films and many shows.
Watching What If? might give you a good start on the multiverse which is a great way to better understand the movie.

You can feel that Sam Raimi, the director better known for Spider-Man and some horror genre movies, did put his way of directing into the movie and that’s great! The CGI is stunning, even for marvel.
Overall you can expect some scare jumps, some madness and a bit of violence. The movie is well paced and delivers on its promises!
As always, That’s a Wrap!