The 'A Killing Joke' comic is appealing because of its depth in character development and the way it challenges conventional comic book tropes. The story is both disturbing and fascinating, making it stand out from the crowd.
Batman: The Killing Joke comic can be valuable. If it's in mint condition and a rare edition, its value can increase significantly. But even common editions have appeal among fans and have a certain worth.
It's a bit of a mixed bag. The violence and themes in Batman: The Killing Joke can make it inappropriate for some. However, if you have a deep interest in the character's evolution and can handle the mature content, then it could be seen as appropriate.
I don't have the exact measurement off the top of my head. Usually, this kind of information can be found on the publisher's website or in comic collecting guides.