One of the most important issues in the history of comics.
This is one of the most significant comics to ever be published. It was the first superhero book published after Timely Comics became Marvel Comics. It’s heralded as the start of the Silver Age, and the re-birth of Superhero comics. The month that it came out, Marvel’s lineup included 3 types of books - anthology books that featured random, unconnected short stories (think Twiligh Zone or Outer Limits stuff) such as Amazing Adventures, Journey Into Mystery and Tales of Suspense, teen romance books aimed at girls, such as Millie the Model, Teenage Romance and Linda Carter, Student Nurse. Finally, they had their old standby, the Western books. These included Gunsmoke Western, Kid Colt Outlaw and The Rawhide Kid.
Fantastic Four #1 really stood out. Not only did it feature the return of the super hero, but for the first time, it really humanized the characters. Batman was a millionaire playboy and Superman was darn near perfect. Heroes of the time never really dealt with struggles in their personal lives until this book. Here we saw Ben Grim, who was ashamed of his monstrous appearance, and Reed dealing with the guilt of having caused Ben’s accident by rushing the launch of his rocket; not taking into account the effects of the cosmic ray storm. It was truly ahead of its time!
All that being said, the story leaves a lot to be desired. It had a lot of potential, but the problem was obvious: they squeezed was could have easily filled two issues - possible three - into a single comic, and the result was a story with tremendous pacing issues. This is particularly noticeable at the end. The FF don't really defeat The Mole Man, they just ran away from him and assumed that would be the end of the threat. Why? He just said that he was going to steal all the nuclear power plants (for reasons not at all explained) and then take over the surface, so why would getting back in your jet and flying away end the threat? They did nothing to this guy. Instead, Mole Man just randomly decided to blow up his island. Pretty weak, to be honest.
So you've got 5 on the importance scale, and a 2 for story; so I figure that's 7 from 2 categories, so 3.5 stars on average, and since story is more important, I'm rounding down to 3.