What does Trello do well? Trello is good for managing a single project at a time with clearly defined swimlanes. It works great in an AGILE environment. Easy to use tool for collaboration between team members reduces friction and enhances communication.
What does Trello not do well? Trello could do with better UI features on tickets and reduced clutter on the UI. It is not good for managing multiple projects with interdependent components since each Project has its own board. One does not get good visibility of all interdependent projects in one view.
What do you wish you had known about Trello before using? Trello itself has limited features but it does support interfacing with other applications that have those features.