I have no problem with a Batman show that takes place before Bruce even becomes Batman. No problem whatsoever. In fact, it would help me fill in the blanks for some characters such as Gordon. I have wanted to know why people "look to him" like a legend, like everyone knows who he is. The origins of Joker, Poison Ivy, Riddler, etc. I already know about Penguin through Batman Forever.
Not sure how much they are going to go into the origins of the Joker; they're kind of exaggerating Poison Ivy's past; they aren't even using her real name. Nygma aka Riddler should be an awesome origin story though..