Invoiless is a great tool. I can't really understand the poor ratings. It was compared with Freshbooks, Quickbooks, and other accounting software, which are quite expensive. That's not accounting software.
As a small business, I've used many simple invoice tools and I haven't seen those types of features.
It does what it says - you can send invoices and keep track of expenses, and even goes beyond invoicing with features such as live chat on the invoices, white label, different payment methods, additional charges for overdue invoices, and so on. Everyone who needs a solution for sending invoices should definitely buy it.