Don't be daunted by the size. It's mostly pictures.
Wonderstruck is made up of two seemingly unrelated stories; Ben's in the written portion, and a mystery girl's in the pictures. The way the two stories come together is truly fascinating, and with all the clues to find, it was one of the most interactive books I've ever read. That being said, the writing, while good, was not extraordinary. Without the added charm of the pictures, this would be a much slower and less entertaining read. I found the plot threads came together a little too easily and perfectly, but the end is charming nevertheless.
Even if it starts out a bit slow, this is book worth reading to the end.
Estimated Reading Level: 4th grade