I like it's multi-functional, supporting Trello, but of all it lets me store tasks and calendar meetings in different flows so i won't miss anything. I was searching for something like this for years!
It's very useful in terms of keeping track of time and knowing what jobs I have to do and when to do them. It's also helpful as I can see what my teammates are doing and whether they have too much or too little work on at any one point.
Ease of use. By far the easiest plugin I have used. Lots of features and the Google Calendar integration is amazing.