I would agree that Iberia is (generally) better for those who have played base Pandemic.
That said, Iberia is just gorgeous, and sometimes the artwork draws in newbies. Also, I demoed it at a local FLGS during International Tabletop Day in late April with two other people who had never played Pandemic. We ended up losing the game, but they both REALLY enjoyed it, a lot.
In the end, I would say that if you have one experienced Pandemic Player at the table, either of them is a good option.
I'm guilty. To be honest the aesthetics of Iberia is the main reason why I have it as an option instead of original Pandemic.