I just bought a set (set #2, I think). I have only applied a couple (to a 1:1000 TOS Enterprise--er, Exeter) and I think they look pretty good. They weren't as fragile as I feared and went on easily. I find that the carrier film shows up a little more than I like, but that may have more to do with the paint job on this particular model than anything else. The big question, of course, is "do they look realistic as battle damage?" And, to that, I say "yes".
I used some on my K Tinga kitbash. I would dig out a little dent in the center where I placed the decal otherwise the pixels of the decal are visible, a wash of black ink fills in the dent and hides the pixels.