I like how easy it was to use for our team members who are not designers or developers as well! It has made creating different formats of emails so much easier than using Adobe products which can be very expensive if you're just starting out with your business' marketing campaigns (or even when trying something new!).
There have been times where we've had issues but they were able fix them quickly without any hassle - no problems at all from us end users/customers in this case though :) We haven't found anything yet specifically dislike about their product other then maybe some minor UI changes could help make things more obvious once again there's nothing really specific either way here :). Marketing campaign management / creation through templates instead having everyone do everything individually;.