I generally consider Fool Moon the weakest book, but I listen to the all in audio, and I tend to run audiobooks in the background pretty much non-stop so I'm usually looking for repeatability, and PG is pretty good for that, Changes on the other hand, great book, but not good for repeatability. I think JB can be forgiven for the quick, slightly hole-y aspect to some of PG since he was trying to set up both Dresden as Warden and Apprentice Molly arcs. I consider Wight Night the weakest of latter books, especially the 'kiss me for power' ending and the bad thermodynamics in the lake freezing, I mean even a conservative calculation for the ice frozen yields an energy parallel to a ton of TNT, the backwash form the fireball would have killed everyone there and the same amount of juice should have been able to obliterate all the bad guys.