I agree with almost everyone here (excluding the Cassie-bashing), the final book didn't feel complete at all to me.
Everyone acted out of character at least a little (but I guess we could chalk that up to the war changing them) and it kind of seems like Rachel's death was just tacked on as a last minute addition. Plus, cliff-hangers ALWAYS suck, especially when they don't really end. She knew she was going to piss off a lot of her readers (hell, she even apologized in her Author's Notes at the end), I kind of have respect for her for making such a gutsy move (that takes balls, especially when she immediately promoted her new series 2 paragraphs later), but I still think it was unfair and a bit of a cop out.