Unfortunately, in spite of all this promise, the film ends up being too serious, without being ambitious enough to handle the gravity of its themes. The problem starts with the writing—whoever finalized the script wasn't confident enough to let the themes stand on their own, so they're constantly repeated in bad hand-waving dialog, a barrage of solemn insights into the characters' thoughts on being The Oppressed and The Other. The whole movie—especially the second half—is a litany of over-serious pronouncements, barely speckled with occasional humorous asides, which aren't really enough to make it seem like the filmmakers have any perspective.
In a film like this—a film about the psychology of oppression and victimization—it's important to focus on motives and interior lives of the characters, and because it's a "strike force team" ensemble movie, the filmmakers had no time whatsoever for that kind of exploration. Sudden changes of loyalty (romances? betrayals?) were constant features of the narrative landscape, but were totally dramatically inert, because they were so quick, and because the characters were lifted and dropped into the plot so frivolously. This type of thing is far better in a comic book format, where you have very short issues, followed by week-long stretches to reflect on those developments. When every introduction and episode is mushed together into 90 minutes, it really feels like nobody cares much about the lives of these characters.
It also doesn't help that there was very little chemistry between many of the younger actors. Raven (Jennifer Lawrence) and Hank (Nicholas Hoult) had lots of breathy exchanges, but there was never any physical or verbal spark between them; on top of that, they were burdened with some very strange encounters involving picnic baskets and massive hypodermic needles. Rose Byrne's Moira was apparently supposed to be romantically interested in Charles Xavier, but this never came through on-screen, making a bit of acknowledgement towards the end seem to come straight out of the blue. These are the kinds of spaces where these characters could have developed into people we really invested in. Instead, they remained mere obligatory plot-points on a well-worn narrative path.