Spoiler Alert: X-Men Days of Future Past

Saw Days of Future Past yesterday.

We start off in a future that looks a heck of a lot like Tron: Legacy; a world of black metropolises and wastelands broken up by occasional glimpses of multicolored light.

The future is controlled by Sentinels, which look a heck of a lot like the Destroyer from Thor: two-story robots colored in black and grey, with morphing-metal bodies and faceless heads that open up to reveal yellow-orange death rays.

In the future, Kitty Pryde, who has the power to walk through solid objects, has somehow learned to use this ability to send people's minds back into their past selves. I should not have to explain that this doesn't make a lick of sense. But since science has decided to act like a cheap harlot to story, the X-Men decide to use this ability to send Wolverine back in time, to stop the shapeshifting Mystique from making an assassination that will induce a panic in the human race and lead them to build the mutant-hunting Sentinels, which will eventually go rogue and kill both mutants and humans.
Wolverine starts his life-saving mission of mercy by killing a room full of gunmen who are angry with his past self for sleeping with a mobster's daughter.
Don't you just love hypocrisy?
Wolverine tracks down Professor X for help, only to discover that Beast has developed a serum that deadens mutant powers but gives the Prof the ability to walk on his own. There are a lot of problems with this: it takes away Beast's tragic nature, and it's kind of a dangerous idea for Beast to intentionally make a serum that could theoretically disable the X-Men. Also, the Professor does little to nothing that requires him to be able to walk again, and if we have a cure for being completely unable to walk, shouldn't we, I don't know, SHARE IT WITH THE WORLD!?
They free Magneto from a prison cell under the Pentagon (how cool is that?) and go to stop Mystique from killing Bolivar Trask, inventor of the Sentinels. Unfortunately, William Stryker, one of the men responsible for turning Wolverine into a killing machine, is guarding Trask, sending Wolverine into a hallucination-filled panic attack. He is thusly incapable of helping stop Magneto from killing Mystique, whose genetics would later be vital to creating the adaptive future-Sentinels. Mystique lives, but the battle was large enough that humankind still gets freaked out about mutants and still try to build the Sentinels.
The X-Men are thusly forced to deal not only with Trask and his Sentinels, but also with an attack by Magneto on the White House, which has some spectacularly grand special effects involved.

In the end, the mutants not only prove themselves as heroes, causing the government to discontinue the Sentinel program and erase their dark future, but also manage to precision-change the events of the original X-Men movies, deleting every controversial death in that series. Gee, what a coincidence!
This film shares an issue with a lot of the superhero films released in the past couple of years: there are more characters than they know what to do with. But there is enough characters with enough screen time and appeal to make the film work.
The primary actors for Wolverine, young and old Professor X, and young and old Magneto are impressive as ever, though I've heard a few complaints about young Magneto being less impressive in this outing.
Mystique is given special emphasis in this film, which I thought was nice change of pace. Though I have no clue how she became such a good fighter between the last film and now; she certainly didn't learn from Magneto.
Quicksilver….oh, Quicksilver. Is he the arrogant, overprotective, conflicted Avenger from the comics? No. Can I take his outfit seriously? Heck, no. But is he awesome? HECK YEAH! Quicksilver is fun and quirky in this film, and is a perfect demonstration of why super speed is an awesome superpower, and probably has the funniest scene the franchise has yet produced. I look forward to his appearance in the next film.

If X2 was about confronting the people who hate you for being different, DoFP is about controlling your own behavior so others have nothing to attack you with. That being said, I still wish Trask would've interacted with the rest of the cast more.
I also enjoyed seeing Blink, the pink-haired girl from the future. As GLaDOS would say...

http://phillymar.deviantart.com/art/Thinking-with-portals-205504247
I was interested to hear she has a five-film contract with Fox. I'm waiting to see what they do with her.
Storm and Beast are both underused, though in Storm's case, they did have to work around Halle Berry's pregnancy.
All the other characters are fairly insignificant; there were even some characters I didn't recognize. That tattooed guy? That kid with spikes in his head in Vietnam? The flaming future kid who could've been Sunspot or Sunfire for all I cared? The film still works, but it feels odd having so many characters who make so little impact.
There are also a somewhat gratuitous number of characters who died since the last film. (Banshee! Nooooooo!)

I liked seeing the film interweave with Nixon and the Watergate era. I also enjoyed the bit of head canon the film supplied me with. If the English monarchy can have werewolf blood, why couldn't JFK be a mutant? I'm glad to hear the next film will take place in the eighties, as I'm enjoying these period piece X-films.
Was this film flawed? Oh, yeah. The science doesn't make sense, it underuses its characters, and it can be a bit hard to keep up with. But you know what? I don't care! Overall, this was a fun, emotionally real film. And given the fan anger at the events of X3, I imagine it will be one of the most popular retcons in recent memory. For once, I'm enjoying Fox's X-Men franchise instead of watching it out of a reluctant loyalty to the comics. I'm particularly glad to see Fox use antagonists other than Magneto, the Brotherhood of Evil Mutants and the government's Weapon X program. So after Silver Samurai and Viper appeared in The Wolverine, and the appearance of the Sentinels here, I'm eagerly looking forward to the looming threat of….Apocalypse!

(And that's why you should always leave after the credits)