The Roomba 690 has a "dumb" bump-and-run tracking system which means that it will run on random paths and will change the course when it bumps against something. Since it cannot find the recharge pad autonomously, the Roomba 690 will run until the battery dies. The 75-minute battery life is not great for this price range, especially considering that you have to charge it manually once the battery runs out. Having said that, it should be mentioned that it's not the lowest battery life for this budget either. One thing that makes this product stand out from the competition is the fact that it's built to be repaired at home, and iRobot has an excellent track record of making spare parts available for a very long time, so you'll be able to keep this robovac for a while.