I really like how Carter and Sadie started to come into their own in The Throne of Fire. Since they shut out the gods and refused their help both characters had to deal with the magical repercussions. They weren't all-powerful anymore and had to develop their own abilities a bit more. I really appreciate that both Sadie and Carter show moments of weakness and consider letting the gods back in, but they resist the urge and end up growing stronger in the process.
The story is finally starting to get good and I like the new cast of characters The Throne of Fire brought in. I actually managed to get attached to a character this time around, so that's an improvement over the previous book.
The Nutshell: I enjoyed The Throne of Fire more than I did The Red Pyramid, but I still wouldn't consider The Kane Chronicles one of my favorite series. Maybe Riordan will blow me away with the final book.