I can't speak to endgame DPS performance (I just got to 80 and am still doing the ShB MSQ), but I can say that ninja gameplay has been surprisingly rewarding—I say surprisingly because I almost always heal in MMOs (but decided to try something different with FF14).
At present (the first two ShB dungeons and the first trial), my damage has been quite good despite not having any experience with these fights. (Of course, I could just be tryharding more than others because I'm into it.) I've not played any other DPS classes in FF14, but I find the burst window nature of ninja to be pretty great—unload in a flurry of rapid beats and then have a lot of flexibility to do mechanics until the next burst window. I don't know how other classes play in terms of pacing, but I would not want to maintain the burst window tempo throughout the whole fight; the opener is fun, but it's a lot, haha!
I also don't feel a desperate need to be #1 DPS in every group that I'm in (though I top dps not infrequently thus far...), but that's probably my healer mentality talking.