Been keeping up with the Marvel Cinematic Universe (MCU)? Hope so, since pretty much all of it shows up in Avengers: Infinity War.
Whatever themes in the MCU movies you may have liked, you'll probably find bits of it in Infinity War. Star-hopping shenanigans from Guardians of the Galaxy and Thor, time bending from Doctor Strange, alien invasions from the earlier Avengers films, Wakandan technology and home turf defense from Black Panther, and so on. If it feels like a bunch of different pieces stitched together, that's because it basically is.
The general arc of the plot is pretty easy to follow for the theoretical viewer who hadn't seen any other MCU films, as best I can tell. Big bad guy is gathering nasty weapons and killing people, try to stop him. But there's a lot of detail that would be missing. Most of that is in terms of character development - there's very little because all the time is being spent on jumping back and forth between all the different groups of heroes doing their separate things. In that way, Infinity War is more like a television series season finale than it is a stand-alone movie.
And like many good season finales, Infinity War ends on a cliff hanger. The heroes don't win, lots of people die, the bad guy is happily retired. Which is very different from the vast majority of MCU films, at least if you think of Infinity War as a stand-alone movie. But it's really part one, with a second part scheduled to come along in 2019. That will be the first episode of the next season, to continue the television series analogy, resolving that cliffhanger and setting things up for the next big storyline.
Like almost all big-budget films that I've seen in the last decade or so, I thought Infinity War was about 30-40 minutes too long. Plenty of character bits that were clearly there just to call back to the earlier movies could have been skipped. Stuff like Drax's "invisible" scene, or some of the Tony-Peter banter...not enough there to define the character relationships, just reminders of what we already know. And of course just about all the fight scenes are extended to show off more explosions and special effects. A bunch of that stuff could have been cut from the theatrical release and put into a director's cut, in my opinion. And was it really necessary to put the post-credits teaser scene (which sets up the Captain Marvel movie) at the very end of the credits?
Despite those annoyances, Infinity War is a fun ride, particularly if you've kept up with all the other MCU films over the last decade or so. It certainly did the job of setting up for the next Avengers film.