Brian Koberlein blogged in “Ugly Theory, Beautiful Data” why he is in the dark matter camp, and not in the MOND camp. He very nicely weights each of the arguments of each theory to conclude why there is compelling evidence for dark matter.
He concludes with:
Of course dark matter still has a serious challenge. It predicts a new kind of matter that we haven’t seen in the lab. It would be nice to make a direct detection of dark matter. This is actually an active area of research. So far there are some interesting hints, but nothing conclusive.