Being a long-time GM for my group of gamers, this book has made my life SO MUCH SIMPLER. I'm good at thinking on my feet and I try to be prepared for anything, but we all know that sometimes players wander off the path you expect, and sometimes you just need a NPC friend or enemy to throw into the mix. This book makes the games easier to keep organized and fantastically more appropriate to the situation.PROS:Pazio has been improving their way of organizing information and it shows in their latest book. They used the same structure that was well received in the Ultimate Equipment book. The info on the edge of the page makes it incredibly easy to flip through this book and find what you need without resorting to the index or the table of contents. I don't spend any time looking for specific page numbers.The NPC's are limited to the core rulebook, but that also keeps things simple. Anything I need to know about one of the pre-generated NPC I know exactly which book to look in. Especially with spell lists, that's important as i don't want to search through 3-4 books to look for a spell listed on this NPC. And on that subject...Spell lists for the caster classes! I can create a NPC in about 5 minutes at this point, having done so dozens of times, but one area I always struggled with were spells. I don't always remember which spells are for which classes and generally don't want to take more time while players are waiting on me just so I have a good selection. Because of that, my NPC casters in the past have been pretty generic and run-of-the-mill. Not so with this book, they have pre-selected spells that make sense and are powerful.Tactics sections for the NPC's. This is a nice cheatsheet for the GM (or whoever is controlling them) that gives them an idea of how the character was intended on being played, and what items/spells/effects would be going on at the start of most combat. This makes playing them on the fly much easier because you already have an idea of what to do.Excellent print quality and a sturdy feel to the book. A few books in the recent past have not impressed me with the quality of the paper and binding of the books. It seems they have gone back to a better printer because the book feels more like the original core rulebook in terms of quality.Items come pre-selected for the NPCs, making it an easy loot table if you wanted it to go that way.CONS:Limited to the core rulebook. I know I already mentioned this makes it easier, but at the same time a few of the books really add to some classes, maybe most notably caster classes. I look forward to a sequel to this.I would have liked if they had provided some base "boss" type NPC's, things purposefully rule-bending in order to really up the difficulty.BOTTOM LINE:If you are the GM, get this book, you'll enjoy it. If you are a player, you could get this book still to have a good basis for quickly creating characters in the future. The builds do make for a nice template if you wanted to use it that way, but overall the value to the typical player is probably limited.Many years ago-- far more than I like to acknowledge!-- TSR published something called "Great book.As much as I like playing GM for games these days, it certainly is getting more complicated to take some time to plan and draft adventures before hand. Between work, study and other responsibilities, it is quite complicated to think on gaming sessions as I used to do when I was younger.That's where this book has provided an unbelievable source of inspiration.Paizo has provided hundreds of NPCs, arranging them by main class, but making use of almost all available class variants to date. This means that even when you have several pages of warriors, you really have a great array of different choices. You get NPCs of almost any level and even if you have to provide a NPC on the fly for a session, you can certainly find many different characters you can use of almost any level.The book is usual Pathfinder quality. Almost all NPCs have their own character drawn with very good art. Covers are paper used for the book are of great quality like all other books from Paizo.This is a great tool, one most GMs will certainly benefit from. And for players, it can provide plenty of ideas for different types of characters.Unfortunately this book is probably the worst Pathfinder product I've ever bought. The big problem is in the design.The NPC Codex takes a mechanistic approach to NPC design: every Core book class has a character detailed for level 1 through 20. So far so good. But instead of thinking about likely NPC roles needed in most campaigns, or giving generic, easily adapted stats, the approach is to give each class/level combo a random race plus a funky, hyper-specific role. Wizards are mosty specialists, likewise.There are about as many Halfling and Gnome NPCs as Humans.So eg I want a mid-level human melee Fighter, ca 4th-8th level, I turn to the relevant section looking for a suitable stat block and getMurderous Halfling - Halfling Fighter 4Cautious Archer - Elf Fighter 5Adventuring Blacksmith - Half-Elf Fighter 6Spell Hunter - Dwarf Fighter 7Fastidious Sharpshooter - Gnome Fighter 8None of these are useable without lots of work to strip away the 'funkiness'. I get the same results with other classes - hundreds of NPCS but there is usually nothing close to what I need. The contrast with the NPC section in the GameMastery Guide is very striking - the GMG NPCs were created with focus on role first, then generic stats, and mostly Human. This makes them easy to use as-is or adapt for specific NPCs at the table, without extensive prep.There may be a way to use the NPC Codex effectively, but it is little or no use to me. Very disappointing.This falls in the category of "extra book": it's not strictly necessary to play Pathfinder, but it's good if you're a master that need a character out of the hat in a matter of seconds.Illustrations follow the usual high quality typical of Paizo.It is not a bad book, simply it's for DMs and players that want to skim through different character builds only.If you don't fall in one of these two categories, save your money for some other exceptional Paizo products.Absolutely brilliant - covers all the main classes for every level, allowing you to have any character you need at a moment's notice. Sure, not ever class has racial variants for the same level, but with most of the work done, simply modifying for races is easy.A must buy IMO.This book is great for a DM who needs instant NPCs or as a guide to new players so that they can see examples of where their characters may progress to.Gone are the days of spending hours statting your NPCs.This book is fantastically organised and is useful for every GM out there!