The thing about X-MEN: THE LAST STAND is that, for all its flaws, it's full of superpowered characters doing superpowered things, which, let's face it, is the biggest reason most of us began reading the comics in the first place. And that's something that better movies often can't find the time (or interest) for.
Not defending it as a great film (though heaven knows, it beats what came after), but as Andrew says, it's not like it's light-years different from Singer's films: they're better, but they're not SO much better that the third one should be regarded as some kind of atrocity; for me, anyway, it was a mild disappointment.