Solidus is a great foundation for bigger ecommerce sites, it gives a lot of defaults for the starter, and has the flexibility for the custom features

1. Free 2. Open Source 3. UI seems very friendly

Solidus is a great program for me to see all of the orders for my store. It breaks it down by day and allows me to see how my team is doing. The quick snapshot of how much the order is on the filtered screen is great for a quick snapshot. Additionally, going into orders allows for a more in-depth look at promotions used, shipping status, and a simple process to do returns, if applicable.