Cavill, however tall he may be, comes across a little on the short side of things, and doesn't really have the proportions of a big guy. Sure he's muscular, but overall, from toe to top, he doesn't come across as big. And one thing that REALLY amuses me is how people keep bringing up where Supermans powers come from, as a way of defending his size, of lack thereof.
EVERYBODY and their sweet old grandmother knows he gets his powers from the sun, that's not to say that the actor portraying him shouldn't look big, powerful and imposing. It's not an argument in any possible way to just state that he's powerful regardless of his physicality. The visual aspect is extremely important regardless of his powers.
A well proportioned body with proper size and definition is necessary for a costume like Supermans and the physicality of the actor helps take away a great deal of the cheesiness of the costume.
In the comics he's drawn like a bodybuilder most of the time, that is a very inappropriate look for a live action movie, however, he should at least look like Hemsworth, or in Cavills case, Evans. Because I gotta tell ya, I saw Captain America and Evans looked ****ing huge. And unfortunately Cavill is not there yet. Cavill does look buff, but nothing impressive.
I have very little doubt that they will enhance his physicality with that software that people kept posting here a while back, which even Hemsworth commented was used to make him look bigger in that shirtless scene of his.
I don't care what they do, how they do it, but just make Superman appear big onscreen.