This is a great title for adding some flavour to a Labyrinth Lord campaign.
I was particularly impressed with the Monster Bestiary, which pulls together an eyebrow-raising number of beasties from H.P. Lovecraft's core stories, his 'Dreamlands' work, and the extended Mythos universe, like the 'serpent people' courtesy of Robert E. Howard.
Another section that really made me sit up was the Random Eldritch Artifacts section, with 99 different weird, un-knowable gew-gaws, 99 different objects they can be, and then 99 side effects. And that was an addendum on the back of the 'proper' named Eldritch Artifact section..!
As ever, it's going to take a good GM to get this stuff to really sing in a campaign, but if you've got the wherewithal to be dealing with Labyrinth Lord in the first place, then you're probably fine on that score.
Personally, I'd love to take this, some Call of Cthulhu material and a few other bits and bobs and construct some kind of fantasy romp through the vaults of Lovecraft's bonkers 'Dreamlands' setting. Ah, one day...