To comment on the first post here, the difference between X-Men and Spiderman is that First Class isn't a reboot. The Spiderman reboot is idiotic for no less than a thousand reasons while First Class is just a prequel.
First Class is the starting of a new X-Men franchise. It's a prequel to X1-3 yes, but it is also a reboot. Apart from the Jackman cameo it's been entirely recast. The future movies in the franchise will add to the reboot side of things as well.
Just wanted to chime in here, I was against the project from the beginning. I went to go see it at the theater and it really just felt like a B-movie that never picked up to A level.
That said, I purchased the blu-ray when it was released and watched it again. Totally different outlook I love the movie! I've watched it a couple times more since buying it. It's one of the few movies that have come out this decade that I could watch over and over because I enjoy it that much. I believe a lot to do with that is the pacing. It's a quick paced movie. Training montage scene is a good example of how the rest of the movie is paced. I like it.
There were of course things that pissed me off about it. The only people who could act were the 3 leads (McAvoy, Fassbender, and even Bacon) Everyone else sucked...but the talent of the 3 leads made up for it. Especially McAvoy and Fassbender. Such great actors. I'm glad Fassbender is getting more recognition finally. Now Jennifer Lawrence, unless she's naked and silent she needs to go away. I can't believe she's getting lead roles in movies. I certainly won't pay to see her "try" to act. January Jones is the same deal. I'm a fan of Mad Men and seen her stiff Kristen Stewart-esque "acting" enough to be instantly tired of her on screen. Her looks/body aren't even enough to keep me interested anymore because I've seen her as Betty Draper for so long I can't stand her and find her attractive.
So yeah! Total 180 on my opinion towards it after getting it on blu-ray. Weird!