A time travel fantasy that begins in 1984 (the year following the novel's publication, by the way), then mostly takes place in 1810 with a brief stint in the 17th century. If you like Egyptian mythology, time travel fiction, stuff involving magic!, 19th century English literature (poetry mostly) and a read that's a seemingly unstopped stream of action scenes, you'll probably enjoy this novel.
It was probably considered to be a ground-breaking, super imaginative piece of fiction in 1983; after all, the only other piece of time traveling fun that existed at the time is Doctor Who (since 1963, people!), and maybe some science-fiction goodness. Hey, Back to the Future came out in 1985!
Personally, though, as a reader from the freaking 21st century, I found the story pretty obvious and predictable. But then again, I am also a fan of entertainment that mucks about with time (Doctor Who!), so my previous experience with the genre probably gave me an advantage over someone who has no previous experience trying to figure out time paradoxes and the like.
Also, I did not really like the fact that a particular chunk (the whole werewolf-thing-that-switches-bodies-with-his-victims-so-that-when-people-think-they-are-killing-the-werewolf-they-are-actually-killing-the-personhood-of-someone-else-while-the-werewolf-lives-on-in-his-victim's-body) of the plot relied on the mind-body dualism thing being real. Which I found a bit annoying. But I also thought that the author dealt with it in an interesting way; since the whole thing was caused by MAGIC!, you could argue that the persons' consciousnesses were switched, and that the nightmares and fragments of information that their body's new occupant received came from the memories, still intact, that were still stored in their brains. And that the reason why they couldn't recognize and know everyone their new body's occupant used to recognize and know is because the new consciousness doesn't quite know yet how to retrieve memories from their new brain.
So yeah, this was an entertaining read indeed.