Our mouse is very sensitive and accurate when moving in the x and y direction. It has superb sensitivity since our accelerometer has good resolution on tilt, giving 300 mV per g. Our scrolling is also functioning well, responding to prominent 'dip' and 'lifting' motions.
When we are doing our mouse casing design we were conscious to make our device ergonomic. It is quite comfortable to hold in the hands, and the mouse buttons are easy to reach on the fingers. Since this is our prototype design, we did not make the mouse cable as long as a real product would. Therefore the user has to be careful not to perform violent motions to jerk and pull the mouse cable. Since our mouse is quite sensitive you don't need too much force to move the cursor. We also only used electrical tape to hold our casing, which in a real product we should make it sturdier for the product not to break.
We found out that another group is doing a similar project of PS/2 keyboard, putting the keys on two seperate egg shaped holder for comfortable key typing. It is possible for us to integrate our design with their design, incorporating our mouse into their eggshell keyboard to have a freehand mouse/keyboard input combo. This exact design was actually not yet implemented on the market, but similar keyboard/mouse designs have been available for people with injured hands. One example company is www.fingerworks.com, however their mouse implementation is finger gesture based, rather than hand motion based like our design.
Our device is very usable and intuitive, and the learning curve is less than seconds.