Physicist Matt Strassler writes:
Over the weekend, someone said to me, breathlessly, that they’d read that “Results from the Large Hadron Collider [LHC] have blown string theory out of the water.” ...Be sure and read the knowledgeable comments. There are pretty much two possibilities -- that string theory makes no testable predictions, and that the LHC has disproved the theory.
Now what’s so silly about this notion that the LHC has ruled out string theory is that the whole reason a lot of people hate string theory is that it doesn’t make any testable predictions! So obviously you can’t rule it out with current experiments… that would require testable predictions!
Strassler defends string theory, but is not a string theorist himself. For a hard core enthusiast and hater of anyone else, see Lumo:
When Michio Kaku or even Brian Greene were explicitly or at least implicitly promising you time machines that will produced because of advances in string theory, they oversold the practical power of string theory. When someone would "promise" that it's guaranteed that an experiment that has already been performed would have to observe some beyond-the-Standard-Model physics, they surely oversold the "urgency" of string-theoretical predictions as well – simply because no BSM physics has been observed yet.Lumo brags about how well the theory works, but cites no published papers to back it up.
However, when Edward Witten "guessed" that the single right string theory compactification capable of predicting all particles' properties would be found within weeks back in 1985, it was just a guess that turned out to be overly optimistic but that reflected this top scientist's best judgement at the moment. There were very good reasons to think so.