Further to my earlier post, there was a recent discussion of this topic at Blogging Heads TV, between Daniel Kaufman (Missouri State Univ.) and Massimo Pigluicci (CUNY) on this topic (h/t Brian Leiter at his blog).
It was a pretty good discussion, and worth the 57 minutes it took to watch and listen. Or you could just listen, as the watching is of talking heads.
At around 4:40, Pigliucci says (as transcribed by me):
Philosophy of science, in particular, is a way to look at the doings
of science from the outside, specifically from the epistemic warrant
perspective. So we want to know, as philosophers, how science
works logically, what is it that scientists take to be sufficient
evidence for their theories, how they construct their theories.
My own criticism of philosophy of science, is that I see them as doing poorly what is mentioned in the second sentence of that quote.
Overall, I agree with these two philosophers on many of the points that they brought up. I do recommend taking the time to listen.
The Heretical Philosopher 