Peter Woit and Lee Smolin have each written books allegedly critical of string theory. I haven't seen them yet because they aren't published here yet. Leonard Susskind, one of the founders of string theory, was interviewed on KQED. He had a defense of string theory and some bad things to say about a couple of unnamed physicists who have got to be Woit and Smolin. This provoked a rather impressive slapdown from Peter at Not even Wrong which includes:
Near the end of the interview, when asked to cite some experimental evidence in favor of string theory he said that yes there was a lot of evidence including:
1. The existence of gravity.
2. The existence of particles.
3. The laws of the universe.
Quite remarkably he then went on to announce that QCD is a string theory and take credit for it, saying that string theory was “invented by Nambu and myself as a theory of protons and neutrons, an extremely successful theory of protons and neutrons”. According to Susskind, string theory provides “the whole explanation of protons and neutrons and nuclear physics” and that “heavy ion collisions are best described in terms of string theory”.
It's really pretty pitiful if the best Susskind can do is petty ad hominem stuff about Peter like:
Well, for example, there’s one fellow who failed as a physicist, never made it as a physicist, became a computer programmer, has been angry all of his life that he never became a physicist and that physicists ignore him, so he’s now taking out his revenge by writing diatribes and polemics against string theory.
Smolin gets no less snarky a dismissal:
There’s another fellow who has his own theory, I won’t tell you who his name is or what his theory is, but he writes lots and lots of theories and his theories go glub, glub, glub to the bottom of the sea before he even gets a chance to put them out there. Physicists don’t take him seriously, he’s angry and so he’s also writing a book complaining…
As Peter says:
UPDATE: Having now heard all of the Susskind interview, I have to say that apart from the cheap shots at the start, and the strange claims at the end, it was pretty good. The most interesting part for me was how he had been a plumber for five years before going to college. He went to school to study engineering, but turned out to have no talent for mechanical drawing (in those pre-computer days).