I just finished Glen Cook's "Sweet Silver Blues," which I've heard described as a (loosely) noir-style mystery in a fantasy setting. This is the way I want to take my own fantasy-mysteries - a period investigator in a fantastic setting, rather than the urban detective in a paranormal contemporary world that seems so popular - so I was particularly interested in this one. It certainly has some elements of a mystery story, and I did like the noir intrusions into a fairly standard fantasy setting, but it didn't strike me as a mystery for one reason: no fair play.
There was no way that a reader could have guessed what was going on before the detective, because most of the time, the background clues, hints and relevant world knowledge was provided only a few pages before the attached solution. I got the impression that I was somehow expected to intuit any number of possible fantastic elements ... or there was no play-along aspect to the mystery.
Since this is the first book, I would expect this to balance out in later novels. Undecided whether I'm going to try to pick up future volumes to see. I was curious to see what would happen, but I didn't feel invested in the characters, so I wasn't interested in their survival ... a loss of tension. I am very very picky about my character development, though, so odds I'm being overly harsh - high.