The movie is a compilation of Twilight and New Moon. The storyline is quite entertaining and the actors are quite impressive too. But, if you are the biggest fan of the original Saga, you'd feel like you're wasting your time and money because the movie is just for fun and it's not for you to compare and contrast to the original scenes.
Well...if you would like to have a change, watching it won't hurt a bit. Just relax and have fun while eating your popcorn. It sure helped me enduring my stress at work...:)