I like the premise, I mean a girl who can make herself look like anyone else, working with other variants, all with unique powers. It is X-men meets a shapeshifter, but like one of my buddies said-- shapeshifter type named Tessa, dejavu anyone? But she is different enough that it def doesn't feel like I am reading Cassie Clare. I was also a little confused about Alec. It was obvious that Tessa liked him, but he has a girlfriend so I don't know what he was thinking. I know they are really close friends and have been for a while, but I think that Kate, his girlfriend and another variant, was rightly jealous when they were together. These things get themselves worked out sort of after lots of heartache. But the cheating is just hard for me to deal with, no matter how much I am cheering for a couple. They had this undeniable chemistry, build up, and the friendship to back things. Speaking of taboo relationships, I didn't like the mystery guy in the plot line. I think it sends a message that kind of relationship is okay, when some things, no matter how romantic forbidden love is, some lines shouldn't be crossed. But on to the characters. I felt for Tessa, and while it was weird, it was also very normal how she got used to, and transitioned right into Madison's life and adopted it as her own. She had a built in family, friends, and people who loved her. She didn't seem to have a lot of that before coming to FEA. It is sad but universal how Tessa wanted to forget certain parts of her past, and embrace the new identity. I think many of us, I know I do, sometimes dream of being able to start over or live someone else's life, and Tessa gets this chance. Seeing her deal with not losing herself was heartbreaking but I got to see her grow so much through it. I liked the theme of friendship, especially the value of female or same sex friendships in this one. Holly is her best friend from FEA, another Variant, and I appreciate how their friendship continued even when they aren't physically near each other. They still supported each other, and I loved that. I also liked to read about what Tessa learns from picking up the friendship between Ana and Madison. The pacing was really good for most of the book but there was a part about 3/4 of the way through that it dragged a bit for me, but as the ending and tying up the loose ends of this plot line started it picked right back up. Speaking of the ending, there is def room for a sequel with pieces of information that came out at the end, but it is thankfully not a huge cliffie. It is just a nice and tied up ending with big sequel potential. Impostor did a great job at the suspense. I didn't know who the killer was and I had different moments where I was suspecting quite a few of the people in the book. It did a great job with that. Bottom Line: Great premise and very suspenseful.