One of the best things about WooCommerce is the slick one page checkout. It's really fast since you don't need to reload any pages and it's smart enough to know when you don't need shipping information when you're only purchasing virtual/downloadable products. We like to make sure the site manager has all of the data available to them so if you have a free download available on your site WooCommerce still asks the user for all of their billing address fields which works great for most users.