The ability to use multiple calendars in one view makes it easy for me. It's also fairly intuitive and doesn't take much training to learn how to navigate through all of its screens. I've only been using this program about two months, but there aren't any features that are disliked by myself or my colleagues who have used it as well. Would recommend trying out an account; it can be helpful when looking at your calendar as well as managing billing/expense reporting.
As far as using the software…