Quite amazingly bad. You keep waiting for the film to provide any reason that the Amy Adams frame story should even exist, but it never comes; she's just reading the book. And it is a very bad book indeed. There is some welcome, albeit unintentional, comedy in the flashback scenes when Gyllenhaal and Adams turn into their own video game avatars.
With his visual talents not fully developed, Almodóvar is not yet Almodóvar. More like a cross between Fassbinder and John Waters. Anyone appalled by the rape scene in "I'm So Excited!" will love the mother selling her son to a pedophilic dentist. I don't know if I find any of it especially funny, but it is strange enough to be engaging.