Don't you think its pretty shit, the fact that Batman's DEADLIEST enemy is the Joker?
He's nasty, but he's essentially just an evil clown.
Then there's the Riddler, who is a million times worse. Then there's the Penguin who, although is the best villain in a Batman film, is essentially crap.
Compare it to X-Men. They fight actually dangerous enemies, like the sentinels or Hulk when he's unstoppable.
In the Marvel vs DC comics, Marvel should have kicked their arses hugely. Didn't Robin win his fight even? ROBIN!