All the idea behind the movie is brilliant. It takes you a while to get curious/excited with the movie but once it gets to you is really amazing. However, it felt like something was missing and ended up disappointing me a bit. I was expecting more, not just from the movie (all the hype and stuff) but from Christopher itself. Still, it deserves a 4/5 because of the construction.
Editing and plot based on a gimmick but I believe it worked out exactly as Nolan planned it. Nolan explored the plot twist in his earlier work and shows here he mastered the craft. The only sad thing about movies like Memento that they don't offer a lot of "re-watch value".