Let's make some things clear

Rating: 6/10 (17 May 2018)

I had a look at like 200 reviews, and they are all rated either 9,10 or 1,2. This only shows that people hardly describe a movie objectively. Still, I believe that the main score of 8.8 is way too much, because after all, this is a superhero movie, which means easy plot, villain against the good guy/s, and good vs evil.
Having this said, this movie was average, not bad but not brilliant. Its target is mostly teenagers or 20yo people, and gives them what they want. There is a lot of action, the story is shallow, but the writers managed to show so many characters in a balanced way. Besides being a movie almost entirely make with CGI which seems to be unavoidable these days ( and that brings away most of the acting) the ending is the part that leaves your mouth bitter. Thanos is an interesting villain, he has a purpose, that in some ways makes sense, he doesn't just kill everyone because he wants to, but in the end it is clear that soon another Marvel movie will come out and it will rewrite entirely this one, because they simply can't kill half of the superheroes. This is a classic of every superhero movie ever: the bad guy needs some artifact to become immortal/god/open a gate to another dimension, the heroes have the chance to defeat him before that but fails, and so the villain becomes God but gets defeated anyway. In this movie is the same. When I exited the cinema I was more annoyed by the fact that another movie will change everything happened in this one than the fact that the bad guy actually wins, and this made me feel that I watched a movie for nothing. I could accept this ending as it is.
People need to keep in mind that the good guys don't always win.
Anyway, as a superhero movie is ok but there are better ones, like V for Vendetta or Wonder woman, but there are others that are much worse, like Green Lantern or Black Panther.
Another thing I should mention is that in order to watch this movie you are supposed to watch almost all the other Marvel movies, or you won't understand many scenes. This can be a good way to connect different movies, but now there are like 18 so it's too much.
I can't say much on the acting, it was ok but the CGI has the main role, and fans don't really care about it.
So to sum up this is an average superhero movie, with a great villain but a silly plot, that relies on random deaths of its characters to cause suspance, which is cheap. I only went to the cinema because I have free tickets, it is only worth the money if you're fan of the series or of special effects.