I can use it without moving my hands away from home-row position, I can drag-n-drop much more easily than a trackpad, middle-clicking and right-clicking are both more consistent, and I can scroll indefinitely in any direction without picking up my hands.
This is probably just me, but when using my laptop on my lap, if I were using the trackpad i would have to bring my hands down closer to my body which is less comfortable, or move my laptop further away from me.
This is probably just me, but when using my laptop on my lap, if I were using the trackpad i would have to bring my hands down closer to my body which is less comfortable, or move my laptop further away from me.