He is often angry, but it never lasts too long. He doesnt have Batman's tantrums simply because they re different characters.
But as i said, he often gets mad and when he does, his eyes light up and turn red. Its scarier than Batman's stare because you know that one more word could get you fried.
Btw, as for the poll, Superman is by definition not dark. Maybe he can be under a villain's control or under the influence of red K or something, but that's it as far as brooding and bad temper and moodiness go.
If by dark you mean troubled, anxious, stressed, having doubts about something, etc, then that's not dark.