I'm a sci-fi writer and reader, although, let's be honest - I'll read just about anything that moves me, regardless of the genre.
I saw the TV version of Hell is Empty after I bought the book. When I realized I had seen the episode (and it sucked), I got a little worried. I'm here to tell you, the book is everything that the TV episode is not, so don't compare the two.
To begin, yes. The premise of the book is a little outrageous - Walk is trekking up to 13,000 ft peaks by himself in the middle of a blizzard, injured and without backup to re-capture some escaped cons. If you think too long on how realistic this all is, you're going to hate the book.
Now normally, I would be the one harping on just how 'realistic' it all is, but then I really got into the dreamlike qualities of the book (something I normally am NOT into). As the book progresses, reality starts to blur and finally, you just don't know what's real and what's not. As a writer, I know how hard it is to write that line between mystical and cheesy, and I think Johnson did it quite well.
I liked the use of the storm and the fire, and Virgil, his there again/not there again guide. It all flowed into something more and fuller than just a ridiculous story. Hell is Empty is about about that grey space between reality and beyond, and I can appreciate that.
I recommend this book, but only if you're willing to open your mind to the possibility that anything is possible.