If you're not familiar with the concept, Paizo's line of pawns for Pathfinder are thick cardboard two-dimensional tokens, with full-colour artwork of a creature printed on both sides. The pawns slot into a base that takes up the same amount of space on a 5' grid as the creature should, so a large-sized creature's token is larger and slots into a large-sized base. The reason this line is so popular is that pawns are an affordable way to amass a practical but handsome-looking collection of monster and NPC tokens. They're easy to use, easy to store, and won't cost the thousands of dollars it would take to amass an equivalent size collection of plastic or metal miniatures.
The Pathfinder Pawns: Monster Codex Box is based on the enormously popular hardcover Monster Codex. In that book, twenty classic races from the Pathfinder RPG were fleshed out and stats were provided for a wide variety of examples of that race: the Core Bestiary has ogres, but the Monster Codex has Ogre Bosses, Ogre Priestesses, Ogre Kings, etc. Accordingly, the pawn set for the book has at least one pawn for every one of those two hundred+ variations, along with multiple tokens for some of the more common ones. To take just one example, the "Gnolls" category is represented by four regular gnoll tokens, three "gnoll bruisers", three hyenas, and then single tokens for 9 other types of gnolls. Each pawn in the set is labelled and numbered for easy sorting, and the back of the box has an index to make things easier. The box includes 20 medium bases and 5 large bases.
If nothing else, the collection is a nice supplement to the pawns presented in the Bestiary pawn collections--it's always helpful to have more tokens of common monsters for larger encounters. But the real value of this particular pawn box is when a GM has a major story arc (or even campaign) that focuses on a particular race of monsters. You don't need ten different variations of an orc if it's just a random wilderness encounter, but if you have PCs invading an orc stronghold, being able to differentiate between "common" orcs, "Orc Sergeants", "Orc Witch Doctors", and the "Orc Warlord" adds a lot to the battlemap. I got this box because I'm running the Rise of the Runelords Adventure Path, and I've been able to make great use of the varieties of Ghouls, Goblins, and Ogres included in the box.
My recommendation would be to scan the list of monster races covered by the Monster Codex, and if you think any of them will have a serious presence in your game, go ahead and pick up this box. The artwork is gorgeous, the variety is excellent, and it's something you can use for any fantasy RPG even if you change games or editions.