My only complaint with Heat was that the author clearly did not yet know that Cordelia was possessed by Jasmine. Had she known, she would've rewritten certain parts and had a different conclusion about certain things.
I can understand the AtS writers wanting the big reveal to be shocking to the fans the way it was to the AI members, but instead of making you want to go back and see all the clues they peppered along the way, it makes you unable to stop seeing things the way you had been seeing them. The Cordy fans couldn't stop seeing Jasmi-Cordy as Cordelia, the Cangel fans couldn't suddenly stop finding the Angel/Jasmi-Cordy scenes as deep or romantic, and AtS fans in general had a hard time placing the truth over what they were led to believe for a year.
Well, not me. I knew SKip was tricking her and that it was going to turn out that she wasn't a "Higher Being" and that things were going to end badly, possibly with her eventual death. For me, it was less of a "Gotcha!" and more of a "I knew it! Well, not knew it in the sense of having the slightest idea but I knew there was something you weren't telling me!"