I find Nite Owl in lacking any character traits that make him particularly likable as a character. As some dude to hang out with? Maybe... even surely. He's 'a swell guy', an okay dude. Inoffensive and he probably buys the beer.
But as a character: all those things that make him a tolerable buddy make him utterly unlikeable. And the Pundit and I will go five more rounds over this... watch!
As for the first part: The movie, for all its relenting grimdark ends on a remarkably upbeat tone. Its an illusion, a trick. You spend so much time in shadows, in grit and grim, in murder and pain and mystery that when the final scene plays out with the world bright and shining and everyone holding hands... you release all the tension built up over the play of the entire plot... to include the fucking resolution. That ninety seconds of sunshine and happy people tricks you into thinking you've had the movie equivilent of an orgasm.
If you walked out over Rorschach's corpse, you'd have left feeling a bit more morose, still trapped in shadows and grimdark.