Is this a great movie ? No !
Is it an awful movie ? Again, no.

It places way more emphasis on effect than on story but within the context of a superhero movie it is ok. Everything is rushed through so that we can get to that final battle. All the elements that should have weight, like Xavier's death, seems just a nuisance to get out of the way. Even Jean's death felt just like a box to tick off. You knew it would be coming.
Magneto has become a one-dimensional, manipulating villain who has become what he claims to be fighting against. And why do all the Brotherhood mutants have to be some kind of tattooed, pierced, made up, leather wearing kind of thug/punk ?
The idea with the cure isn't illogical to me. If it is a genetic mutation it ought to be possible to work something like this up. Within the realm of scifi at least. The illogical part for me is a mutant than erases mutations. Wouldn't he erase his own as well ??
But they boxed themselves in a corner with this story. They killed off or "cured" so many characters that there was hardly anything interesting left.
The end credit scene beeing a foot in the door.