I really dig Discipline.

NIN is great because while all his music shares a feel, each album is inherently different. The Slip, Year Zero, Ghosts, and With Teeth are all very, very different albums. NIN fans will like them all (for the most part), people that arn't long time listeners may really enjoy With Teeth, like Year Zero, but not enjoy Ghosts or The Slip at all - for example.
If you're new to NIN, check out some other albums. They do sound very different, but they're all Nine Inch Nails.
Anywho, I'm really enjoying The Slip. Good stuff.