I like that it has multiple options to choose from, but you can't just pick what works best for YOU! There are different types of billing plans available which is great because there's something out here for everyone (even if they don't know about them yet).
The interface could be improved by adding more color contrast between text boxes/buttons etc., as well as making some buttons larger so people with smaller screens or less sight will have an easier time using this software too. We were looking at having our invoices sent automatically via email instead of printing each invoice individually since we're sending hundreds every month. It was easy enough to set up automatic emails once everything had been setup correctly; however when I realized how much money my monthly bills would go down without manually logging into their website several times per day - i'm not sure why anyone wouldn't want that kind of savings right?