SINNER was not bad, especially when you consider it was a five buck Kindle special: it was an interesting superhero (well, supervillain) novel which engaged my interest enough to read it through in one sitting. Greg Stolze has done some serious crackerjack roleplaying game writing; if you’re into that then you should check this one out.
Grim War was written by Greg Stolze and Ken Hite for the Wild Talents superhero RPG, and it promises to be full of the occult-meets-mutant-meets-Cold-War goodness that I would expect from those two. I’m a sucker for horror/occult spy stuff, to be honest*; I dunno if I’d run a game using that sort of thing, but then one of the deep, dark secrets of the roleplaying community is that we read this stuff for fun even if we’re not going to do an actual campaign about it.
*If you are, too: Declare. Tim Powers. If you haven’t read it yet, do so if you wish to have a pleasant few days.