I have dropped mine onto tile, wood, concrete and cinder block. I have sent it flying across the sidewalk trying to answer it while drunk. I have slept on it, I have smacked it across the room when the morning alarm goes off.
So far I have replaced the faceplate 3 times, the battery door once, the siderails once and taken the trackball apart to clean it once. The only original part is the chin piece/ mic cover. It still works flawlessly.