Sure - but I think that's the least important part of my comment. The preview is basically just an intro to Scheme. I would rather be able to see how well the book covers interesting ideas about deep learning. While the jury is still out, my personal skepticism is that this is a really beautiful passion project that looks great on bookshelves, but that any serious learner would be better served dedicating their time to working through the existing, more traditional, and very high-quality resources available online.