Well, they did say the Killing Joke was one of their main influences, as well as the Long Halloween, and many Batman Fan will tell you that these are the two best Batman graphic novels out there. Given what we've seen, I don't think you should doubt that the Joker will be deep in some way, if the The Killing Joke was truly used for influence, then a bit of his philosophy on life will shine through, and there might be a vague flashback.I mean, dead certain. You surely don't want to focus on the more interesting, and the less likely character to make into the next. Its obvious that you don't want to spend on a character that doesn't have a 100% chance on making to the next film, like Batman does. After all, people go to see these films for the villains, since it is certain Batman is going to be in all of them, so you got plenty of time to learn about Batman, but not a lot of time to see the villains. Especially if they die, like Ra's.
Also, I guess its because I'm not a comic book fan, but I don't buy the whole, he's a killer because he's killer, thing that's going on here. I think, there needs more story to him, and he needs to have real psychological development. I don't accept that he just comes out of nowhere, wearing white make-up with a big gash across his cheaks, with blonde and green hair wearing a Willy Wonka outfit, and there's no given explanation for his look or his behavior. That doesn't make him a character. He's just some event that happens in Bruce Wayne's life. They don't really need a full story. I can accept a little hint, which is what I'm hoping for (in fact, I would prefer little hints to his life, and what made him such a bad man, rather than the full story, that makes him an even more interesting character, because now it leaves you something to think about, something you want to understand, something you begin thinking). Just say something like this thing happened to me, and I started doing whatever, and that'll be perfectly fine. I can put the pieces together after that, and now, he's a real character. I mean, you wouldn't buy someone saying Batman is just Batman because he's Batman (at least I hope you wouldn't buy that). I mean, even Tim Burton went out of the way to show Bruce's parents getting killed.
The point is. I think the Joker really needs to play a large part of this film. Batman is still an important character, but he's old news now, and they need to give a new character, time on the screen. You can't just blow a character off, just because his name isn't in the title. He needs to be more than just some side character who comes out of nowhere and does bad things every 20 minutes. Maybe the Joker played a little too large of a role in the first Batman (then again its Jack Nicholson, and he usually takes the spotlight in any film), but then again, he died.
I have high expectations for this film, and I have no doubt that I will be seeing in several times in theatres (as I did Begins), but I want to look at the Joker in this film and think more than just, "man he looks so wierd," or, "****, he's really insane." I especially don't want to say, "why is he like this?" and get nothing. Maybe some people will buy that, but not me.
Now everyone here is going to flame me.
Also, is Ra's truly dead? They made sure to give him a vague death without a body, and, given his semi-immortal nature in the comics, I wouldn't be surprised if he was dead, but I'm taking his death with a grain of salt (whatever that means).