I've been a Thor fan since the '70s, and I have mixed feelings about the Aaron run. The writing is mostly very good. The art is good. The stories are entertaining. Aaron uses a lot of characters and locations from established Thor continuity, and he uses them well. I didn't want to like Jane Foster as Thor, but I did. And there are some fun new characters. I really only have two problems with the Aaron run. First, he really goes out of his way to tear down Thor the Odinson. Second, he plays very fast and loose with everything about Mjolnir. Posts above have gone into more detail about both of these points. But aside from those two significant complaints, I think very highly of the Aaron run.