we have a 'Roomba', we only use it in our living room because that gets grubbiest. It does a pretty good job, we just put all the small tables, chairs etc onto the sofas and set the little *** loose. It goes right under the sofas and does about 99.9% of what can be seen. It also covers the floor about 4 times and misses nothing. Whether they are worth buying is a matter of price and your wallet.