What I have seen on the Chargers board is he is similar to MM. Calls some boneheaded plays at the wrong time. They blame the loss to the pat's on him whether or not it was his fault.
http://forums.chargers.com/showthread.php?t=39213
If you follow any board after their team loses, you will see the exact same response. If Cam were to have called on LT more, and they lost, you know exactly what the complaint would have been, they should have thrown more and there goes martyball again.
Think about it, they lost not because of any playcalling, it was other mistakes, mistakes that reflect on Marty but not Cam. His playcalling led to an 8 point lead, and a chance to win on the leg of their kicker, despite absolutely stupid bone-headed moves by the Chargers (d.flo headbutt, marlon mcree int, etc.) and dropped passes. If you look at it that way, was the playcalling bad?
And oh yeah, Drew Brees absolutely praised Cam, and he's twice removed from him now.