I found this difficult to get into, and I don't know why. I read other books in the Amdani series, and the Cymraeg translation of Charlie and the Chocolate Factory, while I was trying to read this one, but for some reason it wasn't clicking with me. I would read two pages and put it down. In the end I read it aloud, which is good for pronunciation practice and really sped things along.
The Welsh is a reasonable level for me as a first year sylfaen learner, looking up some words. Lots of repeats of new vocabulary to help you along. The stories are ok, and improve as the book goes on.