Played all compaigns in 5-7 hours. Very challanging, thanks to the new special infected.
Challenging? Heck, it's HARD! Even in Normal difficulty, it was a miracle I survived in The Parish (all other survivors died, due to their "Improved" AI...)
In Dead Center, I died once... due to the "Improved" AI too.
Coulnd't finish Dark Carnival yet :P