Nah, I actually prefer Zizek's underlying philosophy, when it actually appears, which is rare (even if he is essentially rehashing what Adorno said 50 or 60 years ago and peppering it with Lacanian phrases...); but his writing style is superfluous and lacks dignity. When Badiou writes you don't smirk, he's far more real. He's also more concise and organised which, again, allows him to be taken more seriously.
Zizek's too populist which means that people often misunderstand his point. Most people who go to his lectures or read his books continue to hold dear to their narcissistic "tolerant" attitudes - even though Zizek rightly points out that this is a highly aggressive and intolerant subjective position - and continue to dismiss arguments through irony - even though Zizek points out that this is a highly ideological position. The reason he's not taken seriously and probably the reason for his popularity is due to his expository style.