Oh, can't you feel the excitement in the air? It's the summer of 1939. The birds are chirping, the grass is growing, and Superman is starring in his own comic book! Hooray!
Just one problem: the book is just reprinting the Superman comics from the first four issues of Action Comics.
There is a slight exception: Superman's origin story in the first comic is expanded and changed slightly. In Action Comics #1, it's implied, though not stated outright, that Superman grew up in an orphanage. In Superman #1, he's brought to an orphanage by the Kents, who later decide that they simply must adopt him. This gives some better motivation to his becoming Superman. Says Pa Kent: "Now listen to me, Clark! This great strength of yours--you've got to hide it from people or they'll be scared of you!" Says Ma: "But when the proper time comes, you must use it to assist humanity." To make a short story even shorter, Clark becomes very strong as he grows older, and eventually the Kents, already elderly when they adopted Clark, die, and Clark decides that the time has come for Superman to begin his work.
Superman #1 also gives us some insight into how Clark became a reporter. He was seeking a job, and in order to secure it, he went to stop a lynch mob at the county jail, expecting a good story to come of it. That's where he learns that an innocent woman is about to be executed, launching the story told in Action Comics #1.
All in all, the first story in Superman #1 is much better than its counterpart in Action Comics #1. It's just a pity that the other stories in the book are simply reprints. However, that shouldn't be the case in the following issue, so expect greater things to come!
Notes
The first story is an extended version of the story from Action Comics #1. The other stories are just reprints from Action Comics #2, Action Comics #3, and Action Comics #4.
There is a two-page short story, which I actually read, this time, seeing as it features Superman. It's okay, I guess.