Not a big fan of Penguin (what's good about the character?).
Personally, the Penguin is my favorite Batman villain. What's so great about the guy is that out of all of the major rogues, he is the only one who does not have an obsession, compulsion, or really screwed up in the head, and he stands out because of it. He can toe that line between out-right criminal and small time. He is one of the few who can both aid and hinder Batman and Bats lets him do his thing because of it. He is a gangster and one of the few that can actually keep up with the other crazies in Gotham.
I would love to see him done "right" in a future Batman film (Nolan or not).