The plot of the film is simply based around a few points like every other superhero film.
1) A group of people with superpowers find a new one of their kind- 40 minutes of the movie is spent on this.
2) These superpowered people obviously have villains to fight off- The other half of the film is centered around this.
The ending hints at a sequel and in the 2 hours, we also have a few bonding scenes between the characters. Throw in a gay couple to ensure there is diversity, have a diverse cast along with the Oscar winner Charlize Theron and you have a reasonable film!
The trailer might have featured many action scenes but don't expect the film to be an out and out action entertainer.
By the looks of it and the way the story evolves and pans out, one can expect the sequel to be more entertaining, intelligent, and interesting than this if there is a sequel in the first place.
Overall, a one time watch and a more than one time watch for Charlize theron fans! ;) The actor who plays Nile shines too!