Grant Morrison was, at best, a crazy fit for the X-Men. He came onboard at a time when X-Men continuity was extremely tight and tried to make some interesting changes that long term didn’t stick too well. To be fair, at least one of his changes didn’t really make a lot of sense. Having Magneto working undercover in the Xavier School as the mutant Xorn, claiming to be a Chinese mutant healer with a star for a brain, wasn’t a bad idea, and even the helmet blocking the psychic scans of Professor Xavier, Jean Grey, and Emma Frost works, but it never explained how he fooled Wolverine’s advanced senses. Likewise, Morrison’s take on Magneto as some sort of flaky cult leader who had trouble taking out a single NYPD officer with a handgun was rather embarrassing for the longtime friend and foe of the X-Men. No wonder Chris Claremont reversed that whole thing the minute he got back and declared Magneto was never Xorn. Other ideas of Morrison’s, like secondary mutations, the U-Men, and Cassandra Nova had lasting effects to one degree or another, but the final image of his run was Cyclops and Emma Frost making out on top of Jean Grey’s grave…with her approval from some point in the distant future. Yeah, it was a screwy run in many ways, and Morrison’s style of storytelling may not fit too well with Marvel Comics, while DC’s emphasis on spectacle and wonder over personality seems to work out for him fine.
That said, Morrison gave the world Beak during his time on the X-Men, and that alone was a stroke of masterful storytelling.