MailChimp provides videos and step by step instructions supplemented by images for common tasks, offers guidelines and insight into security and spam lawsuits, shares marketing reports, offers live chat support, etc.
They used to have a Wordpress integration, when you could email people based on website activity. It was a very neat feature, and their product team for some unknown reason, decided to drop support for it.
Usually when choosing a service to send your application's emails you need two. One to send the newsletter or news and promotions from the marketing team and the other to send you application's automatic emails and messages. With SendGrid you don't have to choose two because it doubles...
There are some features which are missing by default from SendGrid (sign-up forms or follow-up messages just to name a few). In order to implement those in your emails, you need to know how to program because you have to code them yourself through SendGrid's API.