I disagree with the sentiments regarding 'With Teeth' posted here thus far as well as what TR should do next.
I dig the new, "humble", and more health-conscious TR. His new mindset is all over the lyrics on the new record and it shows a maturing outlook artistically. He can't keep writing The Downward Spiral forever. The lyrics on With Teeth are so about the state of the political climate in this country today (see Getting Smaller; Everyday Is Exactly the Same; Hand That Feeds, of course) that it's relevant and questioning - something all good rock strives to be. For TR to come out being even slightly political is something totally new for him and I find it an exciting step forward.
His new consciousness might lead him to do some interesting music in the future, either under NIN or something else. I don't know much about the Tapeworm stuff but would love to hear the Zach de la Rocha sessions.
To all who are uncertain I would say give 'With Teeth' a few more listens before shelving it.