Something to note before you decide to perform a NG+ is that seemingly certain swords (possibly the unique ones) seems to level up with you much like the enemies. Meaning, your awesome cool level 40 sword with +100 to everything is going to be restricted until you just about finish the game. Again. Otherwise it's pretty slick integration and so far it works just well.
It's also free so there's really no reason to not install it. An important thing to note is that before you can start a New Game + you need to load up a save file and manually save with the DLC installed, only then can you use NG+ with any saved games made after the DLC was installed.

Something to note before you decide to perform a NG+ is that seemingly certain swords (possibly the unique ones) seems to level up with you much like the enemies. Meaning, your awesome cool level 40 sword with +100 to everything is going to be restricted until you just about finish the game. Again. Otherwise it's pretty slick integration and so far it works just well. It's also free so there's really no reason to not install it. An important thing to note is that before you can start a New Game + you need to load up a save file and manually save with the DLC installed, only then can you use NG+ with any saved games made after the DLC was installed.