I think Whedon has good and bad elements. He's not great at taking criticism or seeing his own faults, but he *is* legitimately good at making stuff sometimes. Firefly is amazing, the Buffy TV series was very popular and well-received, the first Avengers movie is great. Even some of his weaker stuff has strong elements (the distinct characters in Alien Resurrection, Ultron in Age of Ultron). And then some of his stuff just isn't good (his contributions to Justice League by all accounts both on-set and on-screen, especially when compared to the Zack Snyder cut).
His complaints about Alien Resurrection aren't entirely out of line - the director they paired with his writing clearly didn't understand his writing well enough, or Whedon's writing wasn't suitable for Jeunet's directorial style, take your pick. I don't know if Jeunet was paired with the script after it was written or if Whedon knew who the director would be before he wrote the script. If it was the former, it's largely the studio's fault for not recognizing that Jeunet was a bad fit for Whedon's writing, and possibly Jeunet's fault for not understanding the material or if he could do it appropriately. If it was the latter, it's also the studio's fault for hiring a writer not suited to Jeunet's style, but also Whedon's fault for not recognizing that he shouldn't be writing for the project if there's no way his "vision" could be appropriately realized. Or maybe the reality is somewhere in the middle, the point is there's a lot of blame to go around and Whedon isn't totally wrong or totally at fault.
I'm not saying he's not a douche sometimes (he is), but Resurrection is a spectacular example of a solid enough script paired with a wildly inappropriate (but still good!) director.
