It is an actual real live Tor double. Good heavens. The cover copy says "two short novels," but I suspect that at least On the Head of a Pin is actually a novella; "one short novel and one novella" is not very good ad copy, though, even if it does give awards voters an accurate idea of what they've read. I suspect, though, that Walter Mosley's main focus is not genre awards. Anyway. Onwards.
The Gift of Fire is a Promethean Messiah story set in inner-city Los Angeles. The L.A. setting is a major strength of Mosley's from past works, but he doesn't have the time here to do more than touch on it--"short" being an operative word--and the flaws of a Messiah story are entirely present here: "kid comes and fixes people's lives and hearts" is pretty hard to make plausible, and also is not all that interesting if you don't believe in the Messiah in question. The template varies some--not all saviors get a pretty girlfriend to screw, for example--but I felt like Minister Faust's latest covered some of the same ground with much more interesting complexity.
On the Head of a Pin was not quite as overtly Messianic, but it did feature a hero who was Just Plain Special Darn It, and how the animatronics were supposed to get to be a spacetime portal, I was never really sure. Unfortunately, what's worse, I also never really cared.
This is not where I would recommend people would start with Mosley. He has much stronger work out there. This pair of shortish bits is more for the Mosley enthusiast than for someone who is trying to see what sort of thing he does for the first time.