If you're looking for the wacky, 1960s Jimmy Olsen, this is not the collection for you. There are no Giant Turtle Men in this collection, no Elastic Lads, no crossdress-disguises.
In most of the first two-thirds of the book, Superman shows up only to watch and muse, "You know, Jimmy's handling it himself pretty well." They are, by and large, charming stories of a teenaged reporter who has earned his place on the Planet, and the biggest discontinuity between this "world" and that of the George Reeves television show is that Jimmy Olsen is occasionally treated with respect, not just by Clark but by Lois and even Perry White.
All of the Olsen pencils are credited to Curt Swan. This series would have been, in effect, his "try-out" for being the primary penciller on the main Superman title. The crisp black-and-white reproduction is probably the best these stories have ever looked.
Volume two, if and when, will be another thing entirely. Jimmy will be well into his goofy stage by then, and he'll be sharing this volume with Lois Lane's solo series (which has an unhealthy fixation on marrying Superman, uncovering his secret identity, or both).
But in this volume, it doesn't seem so odd that Jimmy Olsen would have a fan club.