About the books, the top row where the two green books are. There is a heavy sense of difference in the lighting so the right book looks larger than the left. Assuming they are the same book, this may be an edit you want to look into. Also in regards to an office I would suggest adding a lamp, a night stand/basic counter as well as a couch to make it look a bit more office type. I did some looking back on some real life examples from a few acquaintances and they have a pretty basic sense of style between them with a desk, TV, couch, lamp, CPU, side table, and a small reference of books or CDs. So either way feel free to take my critique to mind if you want a comfortable office/den/living room.