It's pretty easy to set up emails, save headers, footers and elements you want to reuse for drag-and-drop in later campaigns, and to set up new contact data fields, segments, and triggered email paths. It's also easy to incorporate Nosto for product recommendations and set up resends to segments beforehand.
Despite their Magento extension, it was not the easiest implementation, especially with pulling in products for Abandoned Cart. We wanted the product grid to be styled a specific way and not the generic grid which didn't look very nice and our developers had to do this in a specific file on the backend - not something we could have done ourselves as marketers. Also, the extension with Magento is not an API, so the data you can send back to Dotmailer is limited to what they had set up in the extension. If you want to track what page your subscribers are coming from (footer vs. specific landing page) or send additional data points (language preference/profiling consent), you can't because Dotmailer simply won't pull additional information. Shockingly, there's no easy way to track number of New Subscribers - only New Contacts, which is not the same as Subscribers because all Magento customers flow into Dotmailer, so it's counting all customer emails and not people who actively Subscribed. Not sure why an ESP wouldn't have this as a KPI. We've spoken with Support and our PM and no one has been able to provide a solution, so we have not been able to track Subscriber rate/Churn rate, which is ridiculous. Our designer also found the email builder to have default padding and there's no way to change the default, so it has to be removed every single time, which is annoying. If you click into Contacts, by default, it doesn't land on ALL Address Books for whatever reason, but some subcategory folder, which has no address books, so it's an extra click to ALL to see all address books. Then if you click into any of the books, then click back, it lands you back in the default folder, and not the page you were on previously, so it's just an extra step every time that makes it feel quite convoluted. There are several other non-intuitive elements that are similarly annoying.
It's a step above Mailchimp because at least triggered emails are managed in one place. Reporting is not great. It's priced per email - keep in mind this includes all your customers, so this list will grow very quickly.
The ESP we had previously was substandard, so Dotmailer enabled us to do basic ESP things like build an email in the platform vs. inserting HTML, triggered programs, set up resends easily, set up segments easily. Being able to more easily resend and target segments has generated increase in email revenue.