IMHO Acheron is the BEST book in Ms. Kenyon's Dark-Hunter Series! I'd heard this book was good but I thought most of the reviews were a bit too enthusiastic - turns out they were right.
The first half of the book was very hard to get through even knowing the major high (more like low) points ahead of time but getting the background, the who, what, when and where, was worth the reading. You knew ahead of time if Acheron got his own story he would end up with his HEA but it was wonderful to see such a torchered soul find love and peace with his early life.
More than most of the other Dark-Hunter Books I think Archeron could be read as a stand alone book without having read all the previous stories.
I loved it!!