In terms of completeness you've got Iniesta's versatility which has seen him play as a winger and a defensive midfielder which we never saw from Zidane. Even when Zidane wasn't playing in his favoured position it was either as a deep-lying playmaker or from a nominal wide position - quite different to what Iniesta has done. He's clearly a much better defensive player than Zidane. On the other hand you've got Zidane's superior strike and strength and not much else, no?
Iniesta just doesn't seem to have that ability to make the game revolve around him. He started off great in the Euro's and that was set up to be his Euro 2000 equivalent, but it just never happened. He has a good claim for being the best player in that Spanish squad now and he was clearly in good form, he just doesn't have that magnetism that Zidane did. On the one hand Iniesta's work ethic and attitude is hugely admirable in that he doesn't seek the limelight, but on the other hand that does hinder his game as an individual. Zidane was a great team player but very individualistic. Iniesta just isn't, never will be, and because of that he'll never have the singular influence Zidane was capable of.
That said, you'll get a few people coming in here and thinking the comparison's completely laughable and these are the people that have seen little of either player in La Liga, even in the big games...Iniesta consistently makes a mockery of Madrid in a way Zidane rarely did in Spain. There'll be compilation videos showing Iniesta in all his glory a few years after he's retired and that'll be when they realise the depth of his skill. He has a wonderful way of being a class above everyone else on the pitch and yet still doing it in an understated way.
Anyway, for me, the far more interesting comparison is Iniesta and Laudrup.