He is now better than Xavi, but Xavi at his best (2008-1011) was better than Iniesta at his best IMO. A great player anyway, definitely up there with the best midfielders of this century and probably only slightly below Xavi, Pirlo and Zidane. Also, not arrogant on the pitch, doesn't cheat, great at interviews and unlike Xavi/Messi/Barca players never makes pressure to the ref for a booking or sending off.
About Xavi role, I dunno, he operates differently but he has both the technical ability and football intelligence to succeed in every role.