String theory is an intriuging idea but the way I see it, it fails in a few key areas and will not become a "theory of everything." First off, I think it's key failing will be it's attempt to explain gravity in terms of "graviton particles." I think that a new theory will have to be devised to explain gravity and it will most likely have to bridge the gap between matter and time and the distortion effects that gravity has on time. Even worse, string theory has yet to offer a solid explanation for dark matter and it's place in the universe as well as it's apparent "anti-gravity" effect on the universe. Having said that, I think that string theory is great for dealing with bosons and their interactions.