I preordered the big hardcopy of the Tome of Horrors Complete for Swords & Wizardry a few months ago, and downloaded the PDF last night.
Have I read the whole thing? Of course not, and I doubt I will. It's several hundred pages of monsters, I'll flip through it when I need inspiration. When I was young I certainly would have gone through everything, but I can't dedicate that kind of time to a monster manual nowadays.
As for providing inspiration, it does that in droves. I've been staring the prospect of another several hundred dungeon rooms in the face, and it was imposing - but just a few minutes of flipping around and ideas started flowing - many only tangentially related to the monsters I was looking at. It's got enough stuff that there's something to appeal for any given situation.
The collection has a few weaknesses. The first is that a huge percentage of the monsters are from the Fiend Folio and Monster Manual II- and I've already got those. At least I know if it's in this book, it's OGL and I can feel free to stick it in the published levels of the ASE. There's still a bunch of new stuff - I'm particularly fond of the "Skull Spider."
The second is that I don't know that I'll get much use out of the "lairs" that appear with each monster. When I first heard of the "lair" concept I was hoping for little keyed maps - actual lairs. They are actually brief descriptions of an encounter with the creature, I haven't read any that couldn't easily have been made up on the fly. There are several hundred of the things though, and I've only read a handful, so there could be some gems buried in there.
The third weakness is a particular monster I find grating - the "crucifixion spirit"? Seems pretty douchebaggy to me.
The strength of the Tome of Horrors Complete is its size. It's got tons of stuff, so it's great for paging through and looking at stuff when trying to come up with encounter ideas. I don't have the hardcopy yet, but I'm hoping it's bound well enough to put up with my thumbing through it at random.