X-Men: Days of Future Past is based on the 1980 story of the same name by beloved X-Men scribes Chris Claremont and John Byrne. Like many classic X-Men tales, this one features a heavy dose of time travel and a plot with more twists and turns than most intestinal tracts. Returning director Bryan Singer (X-Men, X2) and screenwriter Simon Kinberg streamlined the story, made some noticeable changes, but still managed to tell a complete story while negating a number of issues that have plagued the X-Men film franchise since 1999.

The story takes place in two different time frames. The first is a dystopic, post-apocalyptic future that tends to look more like present day Detroit than some kind of sci-fi trope; the second is a post-Vietnam, early 1970s. The original comic followed Kitty Pryde's (Ellen Page) mind being sent back into her past self to stop Mystique (Jennifer Lawrence) from killing Bolivar Trask (Peter Dinklage) – an event that ripples outward and eventually leads to the destruction of, well, everybody. However, Marvel these days is Wolverine-centric, so in the movie, it's he who travels into his past self to fight the future.

Like other Marvel films, X-Men: Days of Future Past has a certain reliance on campy humor to distract from the plot holes. More recently, the camp has taken over some movies, most noticeably in the latter Iron Man movies, which relied more on slapstick than actual plot or character development. Here, there is much of that same comedy but after the first fifteen minutes of the film, which was simply a very, very long expository speech by Sir Patrick Stewart's Charles Xavier, the audience needed something to let them draw breath.

The humor misses more than it hits and is eventually almost entirely abandoned, say, about thirty minutes in, when the movie actually seems to begin. It's around this time when we're treated to one of the film's best moments: the addition of Quicksilver (Evan Peters). He's a speedster capable of moving so fast he experiences time much slower than those around him. He's the quintessential teenager here – he wears ridiculous clothes, listens to Alice Cooper and Jim Croce, plays arcade games and hates authority – and is infinitely recognizable, even if his powers and shtick are wholesale taken from The Flash and Wally West.

Speedsters are beloved to comic book fans. Their powers are the perfect example of the wish fulfillment aspect of comics, and the audience reacted the best to Quicksilver's Pentagon kitchen scene, which stole the show. Wisely, Days of Future Past doesn't overplay its hand, leaving Quicksilver open to be returned to later.

As Wolverine-centric as the film and comic mediums have become, Kinberg keeps the focus broad, choosing an ensemble rather than a single lead. While Wolverine (Hugh Jackman) is at the center of the movie, he isn't treated as the star. Everyone in the cast is given their moments to shine. The elder Xavier and Magneto (Sir Ian McKellan) are given grand soliloquies to flex their acting muscles and add an air of importance to the proceedings. Likewise, their younger counterparts – James McAvoy and Michael Fassbender respectively – are given an energetic story. McAvoy plays a broken man struggling with an odd addiction made to recall the heroin craze that was beginning to take hold in the early 70s, while Fassbender plays his Magneto to full and decisive villainy. He's not the semi-reasonable anti-hero he was in X-Men: First Class, but a megalomaniac, preaching the same kind of genetic superiority Adolf Hitler espoused. There's a sad irony presented here that the film broaches, but unfortunately does not entirely explore.

Due to the fact this is a superhero/time travel movie, the logical inconsistencies and plot holes are unavoidable. However, it seems too easy to pick apart the flaws in a time travel story. Paradoxes and gaffes tend to come about too easily, and if we can forgive the ones in classics like Back to the Future and Terminator 2, then we should give X-Men: Days of Future Past the same treatment. That's not to say the movies are comparable quality-wise, but they're in the same subgenre at least, and judging one without judging the others is simply unfair.

The film does falter a bit, though in ways much smaller than most of its predecessors. It's easy enough to buy McAvoy as a young Xavier until the two share a scene together and it becomes blatant how different their accents are. At that point it's more like two different characters than different versions of the same man. On the other side, McKellan plays his Magneto as a sad old man trying to live with the mistakes he made as a youth, and we're given that juxtaposition of Fassbender attacking the White House and declaring war on humanity. It ends up making those two disparate versions more cohesive, something the Stewart/McAvoy scene couldn't accomplish as well.

A problem that crops up in ensemble stories is that at some point, someone's going to be left out. Days of Future Past has a great many moving parts, and more cameos than any comic book film before it. Lost in all this is the villain: Bolivar Trask. Peter Dinklage was used almost as much as Hugh Jackman in the promotion of the film, but given very little chance to develop. He's simply the villain. He says villainous things and believes villainous things. If anything, the only thing we learn from him is that the 70s were a horrible time for men's hair and fashion.

The final problem with the film is the Wolverine problem. While he isn't omnipresent, as he was in prior features, the problem stands with the development of his mutant powers. He's too unstoppable. In The Wolverine alone we've watched him withstand an atomic bomb, so any danger he's in now just seems like a joke. In Days of Future Past, sure, he doesn't have his metal bones yet, but that doesn't affect his healing power, which spits the bullets right out of his body before they even have time to cool. (And people have a problem with Superman?!) Despite the heavy danger the X-Men are all in, you can't help but be distracted by the fact that the guy in the middle of all this is invulnerable to an atomic bomb, so the tension just jumps out the window.

The action, however, makes up for this lack of tension. Most of the action scenes come courtesy of Blink (Fan Bingbing), Bishop (Omar Sy), Colossus (Daniel Cudmore), Iceman (Shawn Ashmore) and Sunspot (Adan Canto) in the future, and Mystique, Beast (Nicholas Hoult) and Magneto in the past. The future X-Men work as a cohesive unit, tag-teaming Sentinels and showing off how a team should work rather than the way the former team did in the original trilogy. The action scenes in the past are a little more chaotic – there are emotions running high and civilians to be worried about. It's here where every shot – even common bullets – carry a dangerous dread. Both timeframes acquire different forms of actions scenes, keeping things kinetic and unpredictable while also allowing the separate time periods a personal stamp to continually set them apart.

By the end of the film, the day is saved, and the bad future is averted. However, too many variables changed, and when Wolverine finds himself back in the present, it's no longer the same world he remembers. This is where the film decides to become a reboot and a retcon; two words familiar to any comic reader. Reboots are part of the cultural lexicon now so it's not worth going over here. A retcon is usually just a comic book term. It's short for "retroactive continuity," and is usually used as a magic reset button to undo, well, anything. Both reboots and retcons are used as a crutch in comics and are infamous therefore.

Some retcons are particularly popular (Hal Jordan and Parallax) while others are not (how many times has Jean Grey died?); some reboots are beloved (Crisis on Infinite Earths) while others are reviled (Flashpoint). Days of Future Past marks the first time a comic book movie has attempted a wholesale retcon, essentially erasing X-Men: The Last Stand and the last act of X2: X-Men United so that the characters that were killed are suddenly alive again. Cyclops, Jean Grey and Xavier are all back in the present, and there is a palpable sense of renewal to be felt here. For the first time in years, the main cast of the X-Men franchise is together, promising a steady adventure in the next sequel. For the first time since 1999, the future of the X-Men films looks very exciting.