My student's pretty quick at reading this. For her English level (she's more in the "intermediate" level with regards to school-based fluency tests but still struggles with using the language as she would normally use it), this is really good.

There've been a lot of new words for her (words like ravine, creek, cavern), but the images also really help her to get an understanding of what they mean.

It's also age-appropriate for a 12-year old, especially one who likes magic-based fantasy. This has been one of the biggest difficulties that I've had in finding books for students, honestly. Most suggestions for 'new readers in English' are for really young kids, and a lot of younger teenagers just don't want to read stories intended for kids between the ages of 6-8 (and, if we're honest, a lot of books 'made for' young children are also things young children tend to side-eye quite a lot).