It's easy to use - we used it at our previous work place where I was managing email campaigns daily and had a lot of fun using this software! I have no complaints about the product itself but there were some issues when we upgraded from one version to another (I think they did not upgrade properly).
Our current client uses it and has been very happy so far. Email Marketing Service that integrates well into Salesforce CRM system which makes life easier for me as I can manage all my emails in 1 dashboard instead of having to do them separately.