I developed tendonitis from the pressure i'd use with it. I eventually had to remove the nub so that I couldn't use it and forced myself the use the trackpad instead.
You control how fast it goes by how much force you apply. It’s fairly sensitive too so you don’t need to apply too much. If it still goes too fast, you can always turn the mouse speed down :). It’s pretty much like a touchpad but your finger just stays in place and without the bad parts of typical touchpads. It’s been a couple years since I last used these but I remember them being a lot more comfortable and reliable than every touchpad I’ve ever used (except for maybe the one on my MacBook because that one is actually good)