Wolverine is trapped in some satanic ritual and his soul is sent to Hell while his body becomes possessed by demons and sets out to kill everyone he loves. Meanwhile his soul battles everyone he's ever killed while he tries to escape and get back to Earth to stop the carnage.
The religious storylines that Marvel put some of their best characters through are in my opinion some of the worst books they put out. It's why I was turned off of Ghost Rider when his storyline became all about Hell and damnation or when Punisher got mixed in with angels in the late 90s or in this instance when Wolverine gets sent to Hell. It's strangely dull.
Logan is in Hell for the entire book and so he's constantly fighting throughout the book which gets tiresome after a while. Sure he fights Satan in the end but it's just another fight and after so many fights you think, meh. As for possessed Wolverine, we've all seen that before a few times so again it's another feeling of blasé reading this book.
It's not a terrible book as the writing's not bad, the story is ok, and the artwork is terrific, but it's kind of a weak storyline to have Logan possessed again and fighting demons - it's just not enough to have surface texture, you need depth to make a great comic book.
It's also probably not the best book for new comics readers to start with as there are a few questions reading through it that aren't answered, for example who the Red Right Hand are, or some of the more obscure characters like Puck and Son of Satan. It's not a bad book though not a must read - for fans of Logan only.