I like that it has an easy to use interface, as well as many different templates for letter writing campaigns (e.g., "Thank You" letters).
The only thing is that sometimes you can't find what you need in one place when searching through your account page. For example, if there's something wrong with my logo or website link, then I have no way of knowing where to fix this problem without going back into each campaign individually. It takes time but once we get our first draft written out all at once, everything else flows much easier from here! We are able to write personalized thank-you notes after every event/presentation which makes us look more professional than other companies who send generic emails.