The attitude I get from the Superman trailer is more somber and stoic, which I think fits Superman nicely. I think Man of Steel is going to surprise a lot of people and will be a big enough success to get Justice League on the fast track, maybe a World's Finest movie first.
I think despite Nolan's involvement with overseeing a Justice League movie, he will move past his "dark, grounded" ideals that permeated the Dark Knight trilogy because they simply don't work for Justice League.
Nolan is smart, cold and grounded. Snyder is hyper-action, lots of color, loud. Apparently them combined knocked it out of the park for Man of Steel (that's the word from early screenings), I think it could be a perfect fit for Justice League just like Whedon was for Avengers.