I ran across this post on Fonts.com and thought it succinctly put one of the issues book designers (and web designers) deal with all the time, line length. It’s more than creating a pretty product. If your audience is getting a feeling your material is choppy or they feel like they’re having to slog through the information, your line length may be off. If you care about your book (and I certainly hope you do) you want to do everything you can to create an atmosphere and experience the reader enjoys. If you don’t want to learn about typefaces, line length, leading and a whole raft of other information, you will want to have al designer work with you to create your beautiful book..