Just finished watching it, such an amazing film. It never lets up and everything just flows so well I hardly realized how long it was.
My only minor nitpicks are:
Cap was just kinda...in it? He and Widow move the plot forward, have good fight scenes...and that's about it. I felt like Tony (appropriately) got a great deal of focus, but Cap's reaction to the snap was less intense. Tony seemed destroyed while Cap just seemed stunned. I know, different people, different reactions and all that.
The scene with Ross was unnecessary. No really it felt sort of...forced? Just have the fugitives meet Rhodey and have him agree to help. No need for a phone call with Ross happening at the same time.
Vision was such a dead weight. I get that he was injured for half the movie, but still.
I have faith they'll do Captain Marvel justice in her own movie. They managed to juggle so many heroes in this film expertly that focusing on one should be a cakewalk.
For the next film, it was wasn't lost on me that only the original Avengers are left (Cap, Tony, Widow, Thor, Banner). Assuming Clint wasn't dusted off screen, I hope the next film puts the team (plus Rocket) back together in an interesting way. They were handed a massive loss - as individuals and as a team, so I hope that's reflected in how they behave.
Again, amazing film. I could rewatch it constantly.