I always thought Thor's power varied on where he was. In Asgard he's the 2nd most powerful being (behind Odin), but he's also fighting against all powerful warriors. Also when he goes to some of the other realms, he's extremely powerful, but has powerful opponents.
I think you really get a sense of Thor's power in Avengers. He's pulling his punches against Iron Man, because he has no with to kill a mortal, but just wants to stop him, still we see he can damage Tony's armor with his bare hands, and his head butt, leaves a dent on Tony's face plate.
Then against the Hulk, he fights him for several minutes without Mjolnir and is relatively unharmed, a bit of a bloody nose. Look at Blonsky, when he took the SS serum, he was still left broken into a million pieces after facing the Hulk.
Look at the way Hulk ragdolled Loki, and he was alive, with only a few scrapes to show for it, and Thor is massively more powerful than Loki in fighting strength. Loki has other skills that Thor does not, but Loki is no weakling. Other than getting caught off guard by cap reflecting a bolt back at him from his scepter, he handled Cap pretty easily, and he was trying to get caught.