I really like the idea behind the Meereen chapters in Dance
for the reasons DalekJim
lays out-- they subvert the fantasy trope, make Daenerys a more credible and morally ambiguous character, and offer some striking real-world parallels. But the execution... I don't think it's a coincidence that Dany and Tyrion, whose paths are going to cross eventually, are the two whose stories have the worst pace across Feast
. Meereen, unlike the Wall and King's Landing, doesn't have enough going on politically to justify a ten-chapter arc, especially since Martin refuses to show the Meereenese perspective directly. I like the last Dany chapter-- diarrhea aside, it's a psychological crux for the character, and one that underlines just how unclear her ultimate fate is. I think people expecting the old-dynasy-triumphs resolution from the fantasy cliche handbook are in for a surprise.
Several professional reviews did complain about the pace: The Atlantic
, The New York Times
, and Time
(not Lev Grossman's review, which I'm sure was fawning, but James Poniewozik).
Robb is more popular than his page count (or complexity as a character) would suggest, but I don't think Martin's reputation is for killing off fan favorites so much as for killing off important characters, especially (nominal) heroes. And even that is in the context of epic fantasy, which is pretty bad about never killing anybody over multiple books of endless peril. He doesn't really kill off a lot of characters by general fiction standards.