1 It's about magic
People love magic and it's always fascinating to hear about it or watch it. The movie revolves around a bunch of magicians.
2 The story-line is very good
Movies that involve investigations are often very well done. This movie in particular was spectacular in setting up clues.
3 The realism
The movie is very realistic despite the fact that it's about magicians. The magicians themselves acknowledge the fact that all they do is tricks.
4 The acting is good
The acting is very good in the movie and the chemistry between the characters and how they interact with one another is excellent.
5 Michael Caine and Morgan Freeman
Michael Caine and Morgan Freeman have taken roles in movies together several times and they often meet up very briefly in those movies. However, their involvement in the movie was great and they added additional star power to the movie. (See Why some people like war movies?)
6 The directing is very good
The directing of the movie is very good; leaving very few angles unchecked. It is possibly the best thing about the movie as the movie itself involved the idea of directing.
7 The foreshadowing
While the movie is very difficult to predict, watching the movie more than once reveals the foreshadowing that happened at several points of the first movie.
8 The tricks
Understanding how the tricks were done is fascinating to the audience. It's like any mystery solving situation that most people love.
9 It's unpredictable
No matter how good you are at predicting what happens in movies, Now You See Me is not one of the predictable movies. You have to stay tuned to remotely predict the ending. (See Why Do Some People Like Horror Movies?)
10 Playback value
The movie is an excellent one to watch more than once, especially that with each of the following times you'd watch it, you'd understand more and more of what happened and how.