Loop quantum gravity has been failure. Let us be honest: it has not increased the understanding of gravity, nor that of the standard model. Hundreds of man-years wasted. That is a small amount when compared to string theory, but a failure remains a failure.
Here is the proof: http://arxiv.org/abs/1012.4707, by Carlo Rovelli: "Loop quantum gravity: the first twenty five years". It describes twenty-five years of failure. The author does not describe it that way. But that is the essence of his paper.
For many years, string theory was the only candidate theory of everything. Then, for many years, loop quantum gravity was the only alternative. The truth is simple: neither of them is the right way. Fundamental physics is back at the beginning. The toe is elsewhere.