Worth it
The DLC features 15 new levels, with new and reused assets, 3 new weapons - Fool's Embrace (one-handed weapon), Fool's Lament (two-handed weapon) and Fool's Accord (spear) -, and 2 new sets of clothes for the three main characters (Nier, Kainé and Emil), called Kabuki and Samurai.
The expansion is activated by visiting Nier's house and hanging near the bookcase at the entrance. There, the player is transported to the World of the Recycled Vessel, by the diaries left by Nier's dead wife. These diaries are full of criptic texts and messages, that air in the loading screens between each part of the dlc.
The arenas built mainly on reused assets, as well as new and old enemies and a harder difficulty (than in the main game) make the experience interesting and lengthy.
The main drawback of the DLC is the fact that nothing makes truly sense. When accessing this extension you are deposited into a minimalistic room with two doors. One leads you to a set of five rooms, with monetary and experience rewards, and another leads back into Nier's house. After completing the group of stages, you access another door to another similar challenge, and, after you finish with the rooms, another door is presented, making a total of three entrances with five levels each. This is the fashion in which you play.
Also you can only exit the expansion by either using the door served as an exit, or dying, whichever the case you are automatically transported back into Nier's shack.
Another annoyance is the non-existence of achievements (Xbox 360) or points (PS3). None.
It is also worth mentioning that the protagonist of the expansion is the young version of Nier, as it was featured in Nier Replicant (the exclusive PS3 version in Japan). Although you can only play as him in the DLC, you can't use him in the main game.
Overall it is a beefy addition for the price, with new pieces for the puzzle that is the world of Nier, harder challenges and extras. There are certainly betters expansions, still this one is worth playing if you liked the main game.