Well, it takes a cracking comic to deserve a book this size and this cover price. And you do get all the artwork you need (and a lot more), and all the one-shots, previews, rarities and so on affiliated with the first runs of Fathom, all between these covers. And so you should – it's just that, despite my best efforts, I can't say this is a cracking comic.
Sure, the first arc is near-great – a meaty introduction to a great world, one that effortlessly knocks Aquaman's decades of history into a cocked hat. But it's still not perfect – there's some really poor artwork at key moments, and a problem arising from the art making too many people look the same just when you really need to know who's who. (The script, having two people do the same job at different times, doesn't help there, either.) But that's fine, especially in the light of the second story, of a schizo modern-day Ahab, that really plumbs the depths – it should have been scrubbed from the history books completely. After that we're on firmer ground with some better dips into the whole mythos, and all is right in the end.
As other people have said, this is a huge outlay if you don't know that Fathom is your next favourite book, and at the same time I'm sure most of this is around in other editions somewhere. Having it all in the same volume will only appeal to a certain audience, then – but to them any criticism will not be valid. They'll love it, and adore this book for its very existence. As much as I like and admire what the late creator has given us, I can't say I'm ever going to be such a completist and enthusiast. I'm certainly glad to have had the chance to see it all, but that's as far as it goes with me. Especially with that loon on board...