I like how easy it was to get started using them! They have great customer service and are very quick to respond when you need help setting up your account/solution.
Their support team can be somewhat slow in responding at times but they do eventually answer any questions you may have. We have used their services for our lead generation campaigns as well as email newsletters. The ability to use different templates depending upon what type of content we're creating has really helped us stay organized and make sure everything looks professional.