We have a Roomba, it's probably close to 10 years old.   Lots of parts have been replaced including the battery but it keeps working.   Ours goes twice a week, does a decent job of cleaning, have to empty it by hand and clean the hair out of the brushes.   Half the time it doesn't make it back to it's charging stand, either the battery died or it gets stuck somewhere.  I know at some point ours will get replaced with another Roomba, sure beats pushing a vac around the house.