This offering from Sanderson is aimed at the teenage market, but that is certainly not a bad thing. I loved the Mistborn series, but made the mistake of going from one book to the next, and by the middle of the 3rd it seemed to be dragging, and I gave up. This is not something which will happen with this book once you’re into it, so as long as you know what to expect, I think most adults would enjoy it too.
Joel is fascinated by the magic of the Rithmatists, which he sees studied at his college. Rithmatists use special geometric shapes and creatures which they draw in chalk, and bring magic to. Although Joel is skilled in the drawings, he has no magic, and so can not be a Rithmatist.
When some of the students go missing, and the college is attacked, Joel has to work together with Melody, a Rithmatist apprentice, to try to stop the killer.
Personally, I loved the idea behind the magic, which is basically drawing protective, magical shapes and creatures, to avoid being attacked. This is helped in the book by the illustrations from Ben McSweeney, which include the special shapes used, some of the creatures, and the chapter headings.
The story itself is fast paced, and I would recommend it as an introduction to fantasy for anyone, teen or older, or as a shorter, snappier read for those used to more epic fantasy. There are themes of family and friendship throughout, with a credible world and magic system.