I like that it has such an easy interface for managing our release notes, with tags/categories as well. We have used this service in conjunction of Bugherd's bug tracking system - so we can easily integrate them together seamlessly (and also use their reports). They don't include any custom fields or anything else you might need from your own app; but they do provide everything necessary if those are needed elsewhere too. The price is great compared against other services out there which offer similar features at much higher prices ($300+ per month!).