According to the Guinness Book of Records, X-Men #1 is the highest-selling comic of all time. This was not a surprise, the X-Men were very popular and the comics speculation boom was in full bloom. This mass speculative was based on a fundamental misunderstanding of why things like Action Comics #1 were going for large sums. At the time they were seen as ephemeral, and so therefore when we come to 1991 surviving examples are rare. 1991's hot comics were being printed in their millions and purchased by a buying public that knew how to handle them properly. 23 years later, they're still not rare. They never will be, not in our lifetimes.
This is one of the least interesting things about this arc, though. It's Chris Claremont's last, for now. By now he had ceased plotting the books, and was doing dialogue, frustratedly. Some sniping is possibly apparent here in the "invisible spaceship" that is mentioned in the text.
Given its massive potential audience, what does it do? Does it take advantage of this to tell a compelling story while introducing the concept of the X-Men to a larger audience, like #1s try to do these days? Does it buggery. Yes, we've returned to the X-Men's default status quo, but within that we get a continuity-dense story resting on Magneto's brief time as a baby in 1977.
Today we would call that foolhardy, but in 1991 the book continued to sell, and would pick up readers. Was it a lost opportunity to get even more? Or is it that the modern rhetoric that comics are too hard to get in to does not really explain anything?
The story plays with the idea that the post-1977 Magneto is a different person to the pre-1977 one, because of a genetic alteration by Moira MacTaggert. She used him as an experimental testbed for a treatment for Proteus, her son. What she found was that the use of Magneto's powers made him mad, and what she did was a little tweak to his make-up to make this not a problem. Magneto's new group of Acolytes have found a variance, and Magneto is really quite pissed off at it. Crucial to the storyline's resolution, though, is the fact that this, if it ever worked, wore off (as his attempt at doing the same thing to Cyclops's team of X-Men also wears off, during their fight with Storm's team). Every decision Magneto has made has been his own, even the good ones.
The Magneto in this doesn't quite join up with the last time we'd seen him, in Uncanny #275. There, he looked like he was about to do something, here he's withdrawn and has to be drawn into action by the Acolytes. His interaction with Rogue carries on straight from that, though.
X-Men #1 is at once an odd comic to be the biggest-selling of all time, and yet also an obvious candidate. It had a superstar artist and writer, and is a #1 from the X-franchise. It's not great but neither is it interestingly flawed. It is the end of one era and the start of another (it will continue in publication until issue #275, making it I think the second longest-surviving bronze age comic series after Hellblazer). It is a perfect representation of what was going wrong and right with comics in the early 1990s. I have five.