Heath Ledgers Joker ?

I just recently read a blog about how the author of the blog felt that heath ledgers joker was not worthy of the name Joker. Does any body else feel this way, if so why ? I for one feel that heath ledger took the joker to a new and different level. Despite media hype heath created an interpretation of the joker that will never be seen again, it that my friends is the definition of theatrical genius.