The writing is fluid and extremely rich. No complicated or convoluted turns, but rich vocabularies (Notice to parents, if you want your children to learn new words, put their book in their hands).
The story does not derogate from the classics of fantasy (the child elected, demonic monsters), some characters obey archetypes (The grumpy old mentor, the taciturn warrior). However, if the plot is linear, it is very well done, and quite addictive.
The characters are extremely well-written, engaging and complex enough (for a novel for youth). Many have their cracks, their past demons to face. Personally, my preference is to Salim, alternately funny turn, courageous and touching.
Small special mention to the covers of Jean-Louis Thouard which are absolutely gorgeous.