The most useful feature is being able to track my time very easily, I often forget when using other apps that you cannot keep accurate records of your times in this one! But also it has been easy for me as an employee to access from any where which makes things easier sometimes if i need help with something or have forgotten what we worked on etc.
Sometimes its difficult navigating through some pages but not enough to be annoying really and all features seem fairly intuitive once use them more than twice. Tracking work hours so can see how much overtime people are doing per hour compared to their basic rate of pay without clocking into another app ect.