That was actually the first OHC I ever purchased. This was before I got the collecting bug & was naive. I bought it while still in print only because I was trying to collect all of Magik's appearances.
When the book actually came in the mail I couldn't believe how big it was compared to the New Mutant's Classics I had already purchased.
Then slowly I fell into the abyss of trying to collect every issue of X-Men up until Age of Apocalypse, then came Avengers, Spider-Man, etc...
I had no idea what I was getting into