This thread be hilarious. Jaimie Alexander is very attractive in that poster, but anyone who dumps on Portman needs to watch Closer (or the trailer for Your Highness). In any case, I'm actually happy to see an Oscar winner slumming it in this movie. It reminds me of how Paltrow brought a light into Downey's eyes in the Iron Man movies that gave the movie an airy levity when she was on screen, but the fans didn't notice because they were drooling over Scarlett Johanson (who looked amazing, but had zero chemistry with Downey).
She seems fine for Sif, but I know little of the character and she's going to be barely in the movie. It seems Kat Dennings has a bigger role, so no reason to get upset over a character who will barely be in the movie.