I re-read ACoK recently and I thought they would/should play Qarth a little differently. For me, something that was very underplayed in the book was Dany coming to the Elders of Qarth (can't remember their actual title) and asking for help and being denied. At this point in her story, she's in desperate need of allies and the fact that she asked for Qarth's help and didn't get it didn't form a major part of her time there. I think merging Xaro/The Thirteen with the city elders was a good way to bring that aspect out more.
People are, somewhat understandably, a little suspicious of any deviation from the books. For example, someone, somewhere will end up bitching about TV Xaro not being gay (or being from the Summer Isles) or the Qartheen not crying constantly. What Qarth really needs to do is take her in, hear her ask for help, deny her then force her to turn to the warlocks. Adding in Qaithe and her eventual meeting with Barristan. If it does this whilst being good, dramatic TV, it'll be good.