A few days ago I ran three heroics, Lost city of the tol'vir, Blackrock Caverns and Vortex Pinnacle. All of them took about two hours each. I really enjoyed them, since they were a real challenge. It felt really good when we finaly downed Siamat. But today, just a few hours ago, i ran the last half of Halls of Origination, the last half of Deadmines and all bosses in Shadowfang keep. They weren't nearly as challenging or rewarding (not loot, the good feeling when you down a new boss). We didn't wipe at all in HoO, only once in DM and a few times in Sfk. Okay, Sfk wasn't that easy, but not nearly comparable to the others.
So I wonder, have heroics been nerfed during the night? Or was i just (un)lucky to get three really easy ones today and three hard ones earlier?