Trying to "rate" the fundamental text of Mahayana Buddhism is pretentious beyond belief. So let's assume that if you're here, you knew what you were looking for fairly clearly and we'll not assume that this is anything other than the Treasury of the True Dharma Eye that you thought you were after.
Make no mistake, this work is intended to challenge everything you think about, well, everything. It takes on the nature of reality, the nature of self, the nature the story it just told you and the nature of the book itself. Master Dogen retells stories that perhaps you've already heard and that seem clear and explains why the hero is the villain and how the fool is filled with wisdom and how the thought that just crossed your mind is wrong, wrong, wrong! In fact it doesn't exist! In fact, you never had that thought! Stop all this thinking nonsense you're doing!
He also tells you, in great detail, how to wipe your ass with a stick.
So, it's got that going for it, too.
There are a small handful of English translations of the full Shobogenzo (of which this is volume one of four). Nishijima/Cross' version is the most linguistically exacting. This is both a plus and a minus as it becomes easy to get mired in the weeds of the copious footnotes that are necessary to trying to tease out some of the semantic acrobatics that Dogen so delights in. Having one of Kazuaki Tanahashi's more flowing translations such as "Moon in a Dewdrop" to use to reread the section you just finished really opens the text up and gives the reader the best of both worlds.
And Brad Warner's "Don't Be a Jerk" is a remarkable and insightful (and very funny) modern paraphrasing of sections of Shobogenzo that serves quite wonderfully as a primer on what the other translations are doing.
This is not a book to be raced through or read only once. Read. Sit. Talk to a teacher. Sit some more. Rinse. Repeat. Forever.