Christopher Nolan, producer of the most recent Batman films, has also been handed the Superman franchise. David S. Goyer, his writing partner from the Batman movies, is writing the script for the film, which is called Man of Steel, and which is expected to be released in December, 2012.
I think the opposite - both 300 and *Watchmen *show that Snyder can do comic book action sequences really well, which Superman movies have largely failed on to this point.
In both cases, Snyder adapted a comic book almost exactly. While one may quibble with the plots and/or scripts of those movies, (I happened to like them, but still) he didn’t write them - he just put them on screen.
The script in this case is by David Gover (of Nolan’s Batman Begins/Dark Knight) franchise.
Actually, the main character moving while everything around him is either frozen or in slow motion - that’s pretty much exactly how Superman combat should be staged.
It’s not a matter of muscles, it’s how he holds himself. Christopher Reeve was capable of projecting immense physical strength without being all that bulky.