I liked them because they had different stories than the comics I was reading, and the format was pretty cool. I had the FF story here, but was too young to quite understand what was going on. by the time I was, the book had begun falling apart. I'd like to get another copy of this one some day.
I do own several of them, still, including two copies of the Space Ghost story "The Sorceress of Cyba 3". it was cool to have as a kid, so that I could remember all the names.
however, it's not a very exciting story inside, all things considered. not once does Space Ghost use his power bands! really, what kind of story is that? but the art is pretty cool and it's a neat story.
I also had this one with Frankenstein, Jr. I didn't ever remember seeing his cartoon, but the story was fun. I'm a much bigger fan of Franky now that I am older. I wonder if they did an Impossibles book? that would have rocked.
I also have now a Spider-man, a Hulk, the Shazzan story where he gets a sword in the back and dies (sort of, talk about tramatic) and the Aquaman book. I'll be posting actual pictures when I find them from the bins I moved in. I had the Batman one, and read a bunch more as kids (the Popeye and The Road Runner ones didn't do much for me).