Yeah he was faithful other than the fact that he turned Cyclops, Jean and Storm into 1D interchangeable cardboard cut-outs, turned Wolverine into an incompetent generic tough guy that couldn't back up his bs because he gets his ass handed to him everytime he fights a mutant, made Rogue and Iceman utterly useless to the team and just there for little parlor tricks and a little teeny bopper puppy love story, Mystique and Sabretooth had no personality whatsoever...
few of them even resembled the great characters that they were based on. Half hour eps of the animated series captured the essence of the characters better than 90 minute to 2 hour films by this hack; the writing was mediocre at best and the direction was bland as can be.
Marcus has more substance as a character than anyone other than Magneto and Xavior in those films.
Singer is a hack that never deserved the reigns to begin with...unfortunately most fans were apparently satisfied with bare minimum material...X3 sucked too, but the only difference between that and the first two is it doesn't get a bunch of undeserved ass-kissing.