Why would anyone be surprised that T.O. trashes Donovan McNabb in his book? It's well known that they don't like each other. T.O. is a jerk and has repeatedly been a locker-room cancer in his career.
Having said that, there are elements of truth in his book.
IMO, McNabb was jealous of T.O., and acted out on his jealousy. McNabb is definitely tight in big games. He's a good but not great QB. If you could somehow quantify the physical conditioning of the "top" QBs in the NFL, I wouldn't be surprised if McNabb was in the lower part of the list. And the ugly truth is that, despite all the antics, Owens had his share of supporters on the team. (Though that might have changed over time).
T.O. was never a good fit in Philly. Not sure he'll be a better fit in Dallas, but it'll be interesting!
Kevin