I've recently switched from Mailchimp to Revue.
The UI of Mailchimp felt like a real catastrophe; incredibly complex and unintuitive. Worse, the text editor was a real nightmare to use and embeds were not great at all. Mailchimp basically felt like a Matryoshka doll with screens in screens in screens in screens, to an almost comical point (except it wasn't fun).
Revue is MUCH simpler, has an excellent and easy to use editor, good-looking embeds (links, tweets), also the possibility to create a paid newsletter. In addition, Revue has native integration within Twitter, which is very nice and helps with growth. Revue isn't as powerful as Mailchimp and others around analytics and other features, but I don't mind at this stage.