Do you think this game would be better with a perspective over the shoulder?

It's not simply 3rd person, you can keep aiming nearly as good as in a 1st person perspective, which is needed for a game like this, IMHO.

It's not 1st person and you can see where is the character, which is quite convenient for a stealth game with platforming elements.

I think it could be the best perspective for a game like this, basically it's a compromise solution considering all the elements involved in the game. I'm always puzzled about the combination of platforming elements in a 1st person perspective, despite of having seen then in other games previously like Turok or Mirror's edge.

it could work, but I prefer 1st person.

I haven't played Dishonored yet, but generally I don't like the way crouching people in video games look. I find it unsettling.