Fantastic! Dare I say a must-have addition to an already excellent game system. The base D100 Dungeon v 3.0 is a great improvement over v 2.2 and prior. The Adventurers Companion begins with a nice, easy way to convert any prior version character you want to continue with to v 3.0. Next, it offers an option to quickly create a new v 3.0 character fast-tracked past the first 5 training quests. Rules for Party Play are next. While I had house-ruled this previously when playing with my son, these rules are simple and clear. Tired of always fighting Giant Rats when you roll low on an quest with negative modifier? The Encounter Rule offers a great alternative. Next is an entire Table EA of new monsters to encounter, several with New Abilities. New Hero Races and Hero Paths follow. The comes Withery, an optional but very fun rule set for crafting potions and aanointments from those many parts you loot! A section on making your own quests with a few clever tables follows. Next, a page concisely explaining the various skills. Then a really fun Death Kill table, for granting bonuses when you kill a monster to more than negative 10 HP, including colorful descriptions of said kill. Then, on top of all of that, something Martin could have sold as a stand alone if he wanted, the Campaign. I hate to use the same adjective but can think of nothing else but to say it is fantastic, in every definition of the word. Well done, well written, clear, polished, engaging, deep with fantasy. I will not spoil it for you but I can assure you the story is all that and more. I just finished playing it with my teen-aged son who, like me, has read a great many fantasy novels and played many RPG campaigns. This is a great story. Over and above the new, useful rules, get this book for the Campaign. Enjoy!