As an MCU fan, the last 15 minutes of this movie were me holding back tears. But I also understand it's not a perfect movie and there is definitely criticism you can funnel out of it. Personally, I don't get the criticism about the fanservice. Yes, there was a lot of it, but it felt earned. After all, this was the culmination of stories spanning 20-something movies; it's only natural that it calls back to that build up and, generally speaking, I think it did that well.
The MCU should be a lesson on the importance of sticking to your vision. They had four ensemble movies before - it's scary how easy it could've been for them to blow their load and mess it up. Glad they didn't.
Also, somewhat unrelated, but Kevin Smith did a "review" on Endgame and it's just beautiful seeing a grown ass man tear up at describing scenes of the movie. It's kinda long, but if you're a longtime fan like me and have watched the movies (or don't mind spoilers), you should watch it.