And it's not because Tris died (tho I do am upset about it).
The disappointments I've felt were caused by the following: a bit HOW TRIS died
-- I expected something much stronger, perhaps like how shocking Lelouch's death was in Code Geass R2. Then again, was her death even necessary? WAS IT!? partly of Four's change of character
-- he was just so infuriating once he was outside Chicagothe GD-GP shit
-- idk, I thought some of the arguments were stupid... (and another rather personal issue: the GD acronym would take me a moment to understand because I'd subconsciously always read it as G-Dragon... I'm a kpop fan, okay? XD)my high expectation
-- the mysteries behind the experiment were mostly predictable and the book was boring compared to its predecessors many wtf moments
UGH. I still love the series though, especially because of the first book.