The Plot Twist

I love to read books, but it seems that most of the books I read are pretty predictable.  I would venture to say - formulaic.  So I ask, how important is the plot twist?  In order for a book to be FANTASTIC, is it necessary to have that "thing" that comes out of left field and hits you upside the head?  Or perhaps, is it more important to tell a story well, and plot twists be damned?

As I mentioned yesterday, I am participating in NaNoWriMo and spent last night mapping out my story and flushing out my characters.  I will begin to write today, after the kids are at school.  My issue occurred when I finally went to bed and spent the remainder of the night fretting that the story follows a predictable curve.  My subject matter, however, is NOT something I have seen in books before; but I'm seeing (by the blogs I read!) that there is A LOT out there that I have yet to read! 

So, if I'm dealing with topics like revenge, spiritual beliefs, pedophilia, sex slavery, and the friendship between a little girl of 9 and the kick-ass woman who kills the girl's sick captor; is that "fresh" enough?

I ask you, my wonderful readers, because you all seem to be well versed in current reads and I'd love to hear your opinion!

Good luck to all of you that are also participating in NaNoWriMo, I hope you are successful in finishing what proves to be a dynamic challenge!