This movie is carried by the characters of Magneto, Charles Xavier and Mystique! They are very well played by the actors, especially Michael Fassbender that gives a very emotional and nuanced performance!
It could have been just another excuse to jam several x-men characters in a movie to make money, but instead, we started with characters at their beginning and slowly added layers to their motivations and past! What this does is to efficiently make us care for those characters. There are several dimensions to them. Magneto is not all bad. Xavier is not perfect. Mystique simply wanted to be accepted for being her true self. Because these are things that we all share in our daily lives, we are therefore able to relate to them!
Kudos to the writers and directors of this movie! They made something deeper, instead of the usual run-of-the-mill attempt at using and merging big name just to make a quick dollar!
Sure, there are lesser characters that are not as well played, but they are so secondary that it doesn't really bring anything down.
Well worth getting this movie!