I think these maps are the best thing about The Emerald Spire, and that's saying something because the mega-dungeon itself is pretty awesome, too. My players love the detail and layout of these maps. They are a work of art!
I love this mega-dungeon. I've previous DM'd Rappan Athuk, Temple of Elemental Evil, Tomb of Horrors, Rise of the Runelords, and the more I read through and play this module, the more I love it. Emerald Spire can hang with all of the above adventures, and as a DM, it's my favorite yet. The maps are what makes this particular dungeon really stand out above the rest. They are truly masterful and beautiful to use. I bought the PDF version and upload them to d20pro (virtual table top software). My players think it's the best thing ever, and have commented on how much they love the detail in the maps at least 3 times just in the first dungeon level. The Campaign Cards are nice, but where the product shines is with the Quest Cards. It's nice to be able to hand out reminders of the quests they are on, so the player's don't forget or lose focus about why they are there. And it brings them necessarily back to Fort Inevitable for role-playing experience after quest-completitions.
If you like Pathfinder or Mega-Dungeons, or just great maps, this product is for you!
I would rate this 5 stars if there were more Quest Cards, and less Face Cards. The Item Cards are pretty neat, too… but what makes these cards worth buying are having the Quest Cards to hand out to your players, and hold on to as reminders of why they are in the dungeon in the first place!
PAIZO: More focus on Quest Cards next time, please!
EDIT: I don't understand the extreme low-rating reviews on this product. I find the Quest Cards particularly useful. The Item Cards are also nice: I like using handouts and props in my games, and these cards make difficult-to-find items more accessible as props in the form of cards. I can understand an argument made for 3 Stars, but certainly not anything lower than that.