The interface, which enables you to create your own templates for different workflows; this makes it easy when using value miner in combination with other tools like MS Project or Excel! It can be difficult sometimes if there are too many items/tasks assigned at once - I often have problems keeping track of my tasks while still having visibility into what all has been done so far within each task.
Also not always clear how long one item takes compared to another (eg. creating an invoice vs making calculations). Using value miner together with excel helps me keep everything organized visually as well since i'm already familiar with working in both programs very efficiently now.