Just rewatched the ending of X-Men First Class. As far as origin stories go, it's pretty decent (although a number of continuity issues with the other X-Men movies exist). Charles getting crippled during the time that he and Erik part ways is certainly better than the canon comics story of him getting crippled by a random alien. The use of the Cuban Missile Crisis was also a good idea considering how the timeline matched up with Erik's time in the Nazi camps. It's too bad Magneto's character is tied to that particular time period - as time passes it will get harder to write Magneto stories as we're currently approaching the time when he should be around a hundred years old already. Future reboots might need a new villain altogether or maybe a rewrite of Erik's origin to replace the concentration camp traumas with something else.
Despite the mediocrity of the X-Men movies so far (they're ok, but they're no The Dark Knight) I'm actually fairly excited to see where Bryan Singer is going to take the series with Days of Future Past as all indications point to the present day timeline of the 3 X-Men movies being the dystopian future to the timeline of First Class.
I also wouldn't mind Marvel coming up with a new series with a similar set of origin stories for Charles and Erik (and maybe some of the kids from First Class, but too bad for Darwin lol). Maybe when they have the next "Ultimate" universe eh?