It's not bad, the modern frame doesn't even really change the feel of the story, although the way the rest of the story is presented is also complicated. I recommend reading it, especially if you've seen the movie and enjoyed it.

I was grateful the movie simplified the presentation so that you could really focus on the underlying interesting bits. I left the novel still a little confused as to WTF was going on some regards and the movie makes the essential plot reveals much easier to follow.