I'm really impressed.

Rating: 9/10 (2 May 2019)

Where to begin.
Endgame needed to do A LOT in terms of "landing" characters, and drawing conclusions. After all, this movie is leaving you with impressions that for many of the characters, will be the final one (I'm not calling out deaths here, simply that we don't at this point know if Marvel will make more movies including a lot of the characters here). The stakes have perhaps never been higher for any movie ever made. Do they succeed? Oh yes. Yes they do.
One of the reasons, I believe, is because the actual plot of the movie is genuinly plain and simple: Can we reverse what Thanos did, and also kill him?
While this is by no means an easy task, the simplicity of it allows for the movie to work towards a finale with a 2 hour build-up, that largely centers around quick, well thought out and highly rewarding "dives" into our beloved heroes and their own personal stories, while they try to "solve the problem". And this was a REALLY smart strategic move from the writers/directors, I think. This type of character-first type of approach, makes it easy to bring in a lot of references, which to anyone who's even just seen half of all previous Marvel movies, should result in a permanent mini-grin from beginning to end in fan-service galore. No matter who your favorite hero is, chanced are you'll be very pleased.
In all fairness, the movie is a bit slow in the beginning. At least I can imagine it is for those that don't appreciate all the references as much as I do. But man does it pick up. I don't know who you are or what you have seen before from Marvel, but as said, the plot and the "mission" is simple enough - and the real actual endgame of Endgame will not disappoint you in terms of action, humor, or heartcrunching twists and turns. I laughed, and I cried, all while at the edge of my seat.
I'd say there's no question about whether you should watch it or not. If only to witness a movie never before created, that wraps up 21 others - go watch it. But besides just telling you this, I do want my review to be "helpful" (even though people will anways click those buttons below based on whether they "agree".) But in order to try and be helpful: If you have seen all or most of the movies leading up this and wonder if you should rewatch something before watching Endgame, then I suggest Spiderman Homecoming and Guardians. Maybe even Guardians 2. I won't say they are in any way important to understand any major plot points, but there are references and relationships from these movies that might give Engame a stronger emotional grip on you if you have them fresh in memory. With THAT said, you'll get tidsbits from possibly every single movie from the Infinity saga, so nothing will be wrong in term of warm-up-movies. Those are just my personal recommendations :)
Have fun!