George R. R. Martin's A Dance with Dragons has been out one day. There are now ~20 reviews (as of this writing) on the Amazon website. So we have some information in in terms of reader reaction. The sample size is small, so I don't have a high confidence, but it does look like that Martin has outdone A Feast for Crows. It had been the nadir of this overall series, A Song of Ice and Fire, though some of this might be contrast effect. Book 3, A Storm of Swords seems to have been the fan favorite. In any case, I'll be posting an update in the future when the number of reviews goes north of 100, but here are some charts comparing the five books in the series. The first shows the absolute number of ratings. Since A Dance with Dragons has been out for only a day, the second one shows the proportions.