If you're looking for a read you can easily breeze through, this is not it. There will be struggles to wrestle meaning and memory into the Gaelic language without referring to the glossary at the back of the book. There will be lavish nudity, of both thenubile young and graphically old, and the occasional squick. There will be characters who never act the way you want them to and be downright frustrating. There will be walls of text that attempt to (HORRORS!) teach you things.
If these warnings leave you undaunted, good job because you're in for a treat. The Book of Kells has characters that turn into favorite characters, even if they show up just after the middle of it (Snorri, aw yeah!), and a truly adventurous journey through historic Ireland. Highly satisfying.