I've recently read this book by Peter Woit and can recommend it as an (partial) evaluation of the String Theory programme. Woit's argument is that String Theory has not lived up to the hype of its greatest proponents and that 20 years of continued work have not lead to the breakthroughs which would warrant the dominant position it has in high energy and gravitational physics departments.
A String Theorist, with whom I spoke about the book, was quick to affirm that he himself did not think strings were going to be the fundamental theory, but rather the techniques developed by string theory has actually be useful for conventional QCD. So even if the strong claims, by a minority of String Theorists it was stressed, were mostly hype, he reiterated the argument, "It's the only game in town". Whether this is a compelling argument is not clear to me but Lee Smolin, who has worked in String Theory, would disagree, citing several different approaches to unification in his book which also is critical of the present domination of the String Theory.
I think it's an exciting time to be a physicist despite the apparent stagnation of fundamental particle physics. We are only beginning to plumb the depths of complexity of many-body physics. Quantum computation and information is an example of where whole avenues of phenomena were waiting to be discovered, despite all the work on quantum theory and the foundation of its mathematical principles. Though it's not inventing "new" physics, we are discovering surprising things about the connections between established sub-fields of science. Looking further out, new astronomical observations are raising more questions than they answer, dark matter, the cosmological constant, gamma ray bursts etc. The opportunity to discover important insights is not simply confined to String/M/Brane Theory.