i LOVE the concept. my experience with them is 3 years old so i am thinking (hoping) they have been improved since then. i had two and they would not work. both returned as defective and i got irritated and didn't try again.
but i also gave one to my dad and he loved it. called it his little robot. and he'd let it 'graze' and go back into its little house when done. he did not have a lot of dirt around. i worried that he'd trip over it but he was slow moving with a walker or cane and never had a problem with it to him it was like a house cat.
and i just LOVE clean floors and rugs, don't you? i thought it would be cool to put into an unoccupied room (or in the breakfast room!!!!) and let it vacuum for me and then go back and get it!!!
p.s. sadly, after my dad passed, someone else took the roomba -- i don't know who --
-- and i wanted to try it.
you've got me thinking of getting one again - third time's the charm and all that.