The veneer of fiction doesn't bother me in general. Guy Gavriel Kay does that all the time; in Lions of Al-Rassan, it's obviously an analogue for Muslim Granada, and the three religions he makes up are obviously Judaism, Christianity, and Islam. He seems to do that in order to allow for a hint of magic (and so he doesn't have to worry about being completely historically accurate).
Since I have the book and am looking at a 4-hour plane ride, I'll probably give it a shot, but I appreciate hearing your opinion, since it was purely an impulse buy.