
No. I do not sympathise with the Joker.
FIrst, he had committed too many crimes, and is extremely vicious and evil. He is also cunning and smart.
In “The Dark Knight” we see him robbing a bank. The Joker tricks his “partners” into killing one another, and then he kills the last one himself.
All his partners were killed in the end and he gets all the money too.
( IN THE BANK..)
Happy: Boss told me, when the guy was done, I should take him out. One less share, right?
Grumpy: Funny, he told me something similar. [Grumpy shoots him]Grumpy: I'm betting The Joker told you to kill me soon as we loaded the cash.
Bozo: No. No, no, no. I kill the bus driver.
Grumpy: [confused] Bus driver? What bus dri-? [a school bus drives through the wall and kills Grumpy]
This shows that he is merciless, especially to his partners, making use of them to get what he wants.
Second, he does not care about the innocent. In fact, he kills the innocent without feeling anything.
In “The Dark Knight”, The Joker announced that people will die each day until Batman reveals his identity.
The Joker: [holds camera facing himself] See, this is how crazy Batman's made Gotham! If you want order in Gotham, Batman must take off his mask and turn himself in. Oh, and every day he doesn't, people will die, starting tonight. I'm a man of my word. [laughs]
And the Joker derives pleasure from killing innocent people and inflicting fear in them.
The Joker's victims have included men, women, children – people of all ages. This shows that he doesn’t care about other people.
He is surely an anti-social, inhuman person.
Third, the Joker takes this as all a game. And he actually enjoys it.
In the film The Dark Knight the Joker remarks that he won't kill Batman, because he is just too much fun.
JOKER : You are truly incorruptible, aren't you? Huh? You won't kill me out of some misplaced sense of self-righteousness. And I won't kill you because you're just too much fun. I think you and I are destined to do this forever.
( in another scene..)
Batman : Then why do you want to kill me?
The Joker : [laughs] I don't want to kill you! What would I do without you? Go back to ripping off mob dealers? No, no, NO! No. You... you... complete me.
He also finds it fun to kill people using knifes, and not guns.
JOKER : [to Det. Stephens] Do you want to know why I use a knife? Guns are too quick. You can't savor all the... little emotions. In... you see, in their last moments, people show you who they really are.
The Joker is a serial killer and robber. He is the ultimate villain, who finds joy in going against the law and beating Batman.
However of course, he is not totally bad, or it would be unbelievable and unreal. In fact he doesn’t care about the money at all. He just finds pleasure in doing so.
The Joker: [dialing on a cell phone while a mountain of money burns behind him] Everything burns!
The Joker: Let's put a smile on that face!
In conclusion, The Joker is extremely vicious and evil, killing men, women, children and even his henchman. He kills innocent people without mercy, and enjoys every second of it. He also takes it as a game played with Batman, and finds it fun too.
Therefore, I do not sympathise with the Joker. :D
Source : Wikipedia and Batman Wikia ( http://batman.wikia.com/wiki/The_Joker http://en.wikipedia.org/wiki/The_joker http://en.wikipedia.org/wiki/The_dark_knight )