If I did not like the movie, it was not going to be because Whedon directed it. I've always known that Whedon can direct. He has all of the qualities great directors have. He knows where to point the camera, he can frame great sequences, he is willing to listen to his actors and is able to make necessary changes to his vision if they prove they are correct, and he can do things under budget. The movie just proves that point.
I'm not a fan of his dialog, something that gets a lot of praise. It is not clever to make a pop culture reference when describing something. Clever is finding a novel way to describe something. Clever is not pulling the same bullshit that the writers of those ______ Movies do on a consistent basis. Clever is not talking about better movies that I probably should go see. Tarantino does this too and I'm not a fan either.
I'm not a fan of his original creations. His original creations are sarcastic nerds, which is fine when there is only one of them, but not a whole team of them.
His series, like Buffy, Firefly and Dollhouse, feel unfinished from the first episode and in all cases, it takes around 8 episodes before they have a direction. Angel and Fray were different. Both were in Buffy's Universe and already had established ground rules when he wrote them. The Serenity movie worked better than the Firefly series because the universe was already built and he only used the parts that were necessary for his movie. They felt like they belonged and not cobbled together like in the series.
But, I do not have any problems with the guy. I've met him at the SD comic con and he was willing to spend a few minutes with me talking about his directing style while signing the gift for a friend. He seemed rather taken aback that I considered him a great director, but not a good writer. I guess it was something he did not hear often or at all. He took my criticism of his writing in stride and did not tell me to fuck off, which tells me he is not the delicate flower his fans think he is.