We used mtools in my previous employer as we were providing transportation service using our own fleet of vehicles (Taxi).
The UI was quite good but I dislike that it takes so long before they make changes after being reported by customers/users or if there are any mistakes made with their app like incorrect address etc; sometimes its very frustrating waiting when trying resolve an issue where things have been taken down too soon without giving enough notice! Also some bugs can be hard to track once submitted because most issues get resolved quickly which makes them harder than normal ones - this could just me though since i only worked at one place while solving these problems.