I was a big fan of his in 'Oz' and did not know he was JJJ until i was sat in front of Spider-man at the cinema, man that made me happy.
I agree it would be good to see him played more seriously sometimes though, the scene where he fires Eddie Brock is the only deadly serious scene I can think of he's had, he was real scary there.
He is essential for the role of JJJ.
edit:More scenes with Spider-man too, did he only have the one so far? in Spider-man? Shocking, we need some banter traded between them.