It's free, and the project is active and well-maintained, which means lots of updates are made to the software almost every week. Some of the features are basic (like only showing a list of functions), but other features are quite advanced (such as having an auto-generating class diagram). I don't like how sometimes the website loads really slow, especially when there are lots of comments/reviews in between. It would be nice if the comment box could be moved outside of the page on mobile devices, so you don't have to scroll through all those comments just to see what someone else said about your code. A lot of people use it to document their projects. The benefits include being able to read up on the code quickly, without having to search through documentation that might not exist or outdated.