Reasons to be Optimistic
Zack Snyder's last superhero film Watchmen was very good. Michael Shannon is Zod, and that is brilliant. The rest of the cast is pretty good too. Christopher Nolan is producing so it should have Dark Knight style.
Reasons to be Pessimistic
Zack Snyder's last film Sucker Punch was self-indulgent rubbish. Henry Cavill has a poor track record as a lead actor. The Dark Knight style of realism doesn't really suit Superman.