Last night I finished reading The Swan Maiden by Jules Watson. It took me a while to get into the book, maybe 100 pages before I felt like I was really invested in the characters and plot. Throughout the book there were passages that I skimmed and I think overall the book would have benefited from an editor determined to make it 75-100 pages shorter.
However, once I got into the story I really did enjoy it. The characters had enough depth to be believable as people, whereas reading the old myth you often just get the bare bones of the events. If you like Juliet Marillier, I think you'll find this comparable; although not as elegant as Marillier, Watson's story certainly falls into that same category of romantic mythology.
The book has 4.5 stars on Amazon.com customer reviews, but I think the most insightful comment I saw is from Publishers Weekly: "This modern retelling of a tragic Irish myth is rich in well-researched detail but moves too slowly and reverently."
I did find the last 100 pages or so to be stunning; whether Watson finally hit her stride or the pace of the story just picked up, I couldn't put it down for that last bit and found the ending to be compelling and well worth the read.