The good thing is that it is reliable and seems to work well. Buttons are responsive and are consistent from one to the another. The charge lasts an entire day, however it would be nice to have a battery backup in case the charge wears off during an important exam. The downsides are that the charging cable does not connect direct to a wall outlet, but only to a computer or USB hub. It's also difficult to learn how to use. The up side is that it is allowed for use during the SAT or ACT test and it is clearly a quality product that should last many years. It is required for use in many high school Geometry classes.