I often look down on these codices because they’re a different kind of cash grab, a book of NPCs which is one of the easiest things to publish. It’s been done many times in many games over many years. Like 76 Patrons for Traveller but Rogues Gallery by TSR was more interesting due to the PCs of various employees being included.
NPC turned out to be very helpful within 24 hours for me. Originally I bought it out of boredom and later versions (I’ll get to them) were impressive. I needed an NPC Druid to plague someone so I took one from here, made only a few modifications and boom, now the PCs have a nuisance opponent. If I were 30 years younger, I could’ve saved myself the money and do it all from scratch but this speeds it up even though the NPCs are based upon a model I don’t normally use (the stat array with an 8 and I think a 15, I prefer allocating points).
In addition to decking out all the core 11 classes from level 1 to 20, they included the NPC classes from 1 to 10; get some variety on Aristocrats and Warriors.
Worth buying but the PDF will do the trick for most GMs.