At best, DLC is at least as good as the game its attached to, but most of the time it ends up being worse. There are, however, instances of downloadable content packs that build upon the core game, and ultimately provide a better experience than anything the original title had to offer. The Traitor's Keep Quest Pack for Fable III is exactly that. It provides a perfect summation of what Fable III is all about while incorporating tons of great ideas that ultimately make it a markedly better experience than the original quest.
Things kick off after the showdown at the end of Fable III. Your king or queen has defeated the Crawler and their life has become quite boring until another attempt at revolution is unveiled. The king must then venture to Traitor's Keep, Albion's maximum security prison, to track down the conspirators.
From there you visit new locales and fight new monsters ranging from exploding robot dogs to poison balverines. All the new enemies are a lot of fun to fight and the difficulty has really been ramped up. Considering how easy everything else in Fable III, the added challenge is quite a welcome change.
As you search for the three main conspirators in the new plot to usurp the throne, you'll have the chance to uncover new information that serves to really flesh out their reasons for trying to overthrow you, and you'll realize that their revolution is much different from your own. Additionally, once you finally track down each rebel, you'll be faced with a straightforward moral choice.
The main quest will last you about two or three hours, but there are numerous new side quests, as well as three rather large new areas to explore. The Traitor's Keep Quest Pack offer quite a bit of entirely new content, making the 560 Microsoft Points ($7) easily justified.
Traitor's Keep is a shining example of what DLC can be when done right. It's relatively inexpensive, and introduces a lot of cool new ideas, but more importantly, it fits in with the core game very well. The gameplay is quite improved, especially when it comes to the challenging combat, and the humorous and intriguing story serves as a fitting epilogue to Fable III.