Whenever anyone mentions NKS I'm always reminded of Cosma Shalizi's brilliant and hilarious review, 'A Rare Blend of Monster Raving Egomania and Utter Batshit Insanity'.
For "someone who was once a respectable physicist", yes.
Especially to the extent he's putting resources into this instead of Mathematica.
(Note: the above is from the author's (and others) point of view; I've not read the book and have no first hand opinion on it or Wolfram, besides the law-suit happy thing and such, e.g. I don't use Wolfram Alpha because they own whatever is the output of it, I don't and am restricted in how I can use it.)
http://www.cscs.umich.edu/~crshalizi/reviews/wolfram/