Not Worth the Time
Frankly, I'm mystified at how popular the Marvel Family was during the Golden Age. I mean, Whiz comics in general tended to be a little silly, but when it comes down to it the Superman Family did everything the Marvels did, but better.
When the Marvel Family was given it's own comic, predictably, the silliness increases dramatically. Old Shazam carves in entire paragraphs with a hammer and chisel upon the Rock of Eternity, relating the origins of each of the Marvels, and how it took him 5,000 years to dream up the idea of giving powers to a kid.
Meanwhile, his first creation, Mighty Adam AKA Black Adam shows up after flying at light speed for 5,000 years. Uncle Marvel (of all people) fools him with a trick even Mxyztplk wouldn't even fall for and the fight's over forever.
Really, even judged by Golden Age standards, it just doesn't hold up.