GUI is beautiful. Simple and easy setup. Attaching an invoice to an agreement is a great feature as well.

There are some restrictions, and it's hard to take advantage of some unlimited features. I wan to simply send an invoice to a customer without a workaround or tying it to a project.

In my line of work, selling digital goods, I don't necessarily need a project setup to send one off invoices.

While the AppSumo deal is half off for some upgrades, I don't personally have an interest in it.