Despite the dire circumstances, there's quite a bit of humour in the film and most of it hits the mark. I especially liked the interactions of Thor with the Guardians of the Galaxy cast; they were really funny. As for my problems with the movie, well... as you can see from the poster, there are a lot of characters and since I haven't seen all of the films, I didn't know who some of them were or know why they were acting the way they were. Also, with so many characters to follow, the movie keeps jumping about- not only between earth and outer space, but at a bunch of different places in outer space as well. I'm sure however, that this would be less of a problem for those who knew what all of these places were and who all the people in these scenes were. Also, Thanos was a good villain, one who could articulate his motivations which actually make sense, if you're a murderous psycho.
To sum up, I had a surprisingly good time at Infinity Wars which managed to be quite funny without detracting from the more poignant, serious moments. This certainly gives the film points over The Last Jedi, where most of the humour comes across as forced, awkward, and a bit desperate. If nothing else, Infinity Wars made me want to go back and see a few of the movies I missed, like Dr. Strange and one or two others. Maybe one of these days.