It is quite possible that this is my favorite book from King so far.
Misery is a harrowing, terrifying read made scarier by the fact that it's all completely plausible, not a single mystical or 'spooky' element. The way the story is told, the change in perspective at times, the uncertainty of a narrator working with limited information and a transforming mental state - all of it was top notch.
You'll need a strong stomach for it, but ultimately I highly recommend Misery.