I have been using this software for about 12 years now, as well as over 20 different clients to help with their accounting needs! It is easy to use both online (browser) or desktop version; it has saved me so much time in tracking invoices from customers/clients that need payment reminders sent via email vs paper files, etc...it also helps keep my records current when compared against other services where there are problems with missing data fields & errors being tracked incorrectly - which leads to mistakes made by client's employees who don't know how things should be done correctly due to incorrect information.
This saves us money too because we no longer get calls asking questions like "where did you send our invoice?".