I read the Delirium series before the Divergent one and my first thought while starting the latter was that this is the SAME thing because almost   everything from the dystopian setting and the aptitude test to the heroine's description is similar but even though I had a great time reading both, the Delirium series totally lame ending ruined everything plus I didn't like Lena much. I wanted her to end up with Alex but the way she managed her other love interest was incredibly selfish and didn't satisfy me. The cliffhanger ending of book 1 and Alex and Lena's forbidden romance(I am fully aware of the cliche of it but I still love it anyway) were memorable. As for the Divergent series, I like Tris better but she seems way too cold and emotionless sometimes. She seems much more human in the movie. Her being in a relationship with her instructor(Four/Tobias)is the best part(like in the Vampire Academy series)! I am still in the middle of the last book though and I hope this ending is not an epic disappointment!