One of our e-commerce websites currently runs on Episerver Digital Commerce. Episerver was implemented a couple years back to replace an older e-commerce website that had poor functionality and very limited flexibility. It was put in place to improve the current e-commerce experience as well as put the business in a position to grow and expand its digital offerings.
I did evaluate other products in addition to Episerver. The other finalist was Magento, which has a very robust cart and a large market share. I have used that platform in the past and overall had been happy with it's performance. I ultimately selected Episerver because it was .NET (versus PHP) and had very strong commerce and content components. Magento would have required an integration with another (second) platform to build out non-commerce content in the way that was necessary for the project's needs. Episerver had that out of the box. Plus Episerver's evolution and road map showed solid growth and innovation while at the same time Magento was well behind their plans to launch Magento 2.0 after already significant delays.
Episerver is well suited for customers that need both a strong CMS and strong commerce offering. Most platforms skew in one direction or the other, either focusing on a shopping cart or content. Episerver provides a very solid offering in both categories, which makes it a great choice for a business that needs both but wants to avoid integrating two different platforms together.