It is really interesting to see how much the X-Men have changed over the years. True, the Avengers quickly replaced all of their major members, but nobody ever really leaves the Avengers (except the Hulk), so Thor, Iron Man, and Captain America make it back for the parties and such. But Angel, Beast and Iceman really have been long gone, and the Uncanny X-Men gave way to the All-New All-Different X-Men with Storm, Wolverine, Nightcrawler, Colossus and the rest giving the group of merry mutants an international flare. This second volume in the Marvel Masterworks series devoted to the X-Men collects issues 11-21. This means the end of Stan Lee's run as the writer of the comic book, with Roy Thomas taking over in issue #22. Jack Kirby does the layouts and/or pencils through issue #17 at which point Werner Roth moved from pencils Kirby's layouts to doing is own pencils. It was Roth who was the artist when I first started reading "The X-Men," so to me he is sort of the "original" artist for the book.
There are a trio of classic multi-part stories in this collection. The first is the two-part story #12-13, "The Origin of Professor X!" and "Where Walks the Juggernaut!" After Magneto (#10), the Juggernaut was probably the second most important supervillain in the X-Man mythology, although compared to the master of magnetism everybody is a poor second. We also have the first appearance of the Sentinels in a trilogy (#14-16), characters that would end up in some of the best X-Men stories of all time, and another encounter with Magneto (#17-18). Then you can throw into the mix the Mimic (#19), who combines all of the powers of the original X-Men (think the Super Skrull), and the flashback story of how Professor X lost his legs (#20).
Actually, I was surprised how many good stories ended up in this collection. I would have said there was a big mix of hits and misses until Jim Steranko and Neal Adams showed up to draw "The X-Men," but you cannot dismiss the major characters who are introduced during this period. The sophomore year for the students at Charles Xavier's school was pretty good. Lee left this book on the upswing.