Last time I brought this album up, I was nearly laughed out of here, but I agree: the singer's voice works brilliantly for the theatrical emo-pop of their first album, but on Pretty.Odd. it sits totally askew on all tracks bar the first single.
Also, the fact that they alienated a hardcore following of young teenagers in order to do something more inventive and somehow more worthy when everyone expected otherwise has to be commended, and the only reason they managed to pull it off (mostly) is because beyond the scene and the fanbase, they're all pretty adept musicians and are therefore capable of writing decent tunes, no matter how grating the voice that leads them is.
Basically, they all grew up a bit, stopped fawning at the altar of Pete Wentz, started listening to the Kinks et al, discovered pot and antagonised an army of emo girls. Credit due, methinks.