Earlier quoted context omitted.
the malware point is moot. malware can steals passwords saved, which are optionally saved encrypted. the cert at least in the one browser i checked is always encrypted. and even then, if you have malware in your box, any and all security measures are worthless at this point. decent Renegotiation and mobile client support will come if people using that on the desktop request the feature. it's like that for everything…
What I meant about malware is that client certificates can't provide additional security over passwords because malware can easily steal both. So it's only hassle and no advantage, hence, useless
Also, the client cert, as with private keys, allows you to memorize ONLY ONE password (make it a passphrase, please) instead of a bazillion (or, gasp, reusing).
So, no, it's not an extra hassle. it's a solution for the real hassle of passwords in websites. if it was used.