The ability for all team members in our organization including remote employees can access work items at any time from anywhere with their mobile devices is by far one of my favorite things about this application! I would like more customization options such as different color themes/icons that could be used throughout the app instead of just black text.
Also it's not possible to set up an alert when someone has been assigned to complete a specific project item which we use extensively across multiple projects (and therefore need to keep updated). It also doesn't allow you to create custom views so sometimes it becomes difficult to find what information your looking for if there isn't already columns pre-defined. However, once you figure out how best to customize each view the benefits are worth it! This allows us to easily communicate progress updates via emails without having to rely solely upon other applications.