I *love* my Roomba. My place is too big for one robot so I have it clean the living area regularly and then move and trigger it manually when I want it to do the back rooms. Virtual walls and lighthouses are a must to help it, especially if you have large open rooms. It can get wedged under my cabinet lips so I keep it out of kitchen and just do that part manually.
iRobot's CS is also really damn good. Not too long after I got it the thing rolled through some soft cat poop (fuck you cats!) and got fried while I was trying to clean it. They sent me parts to swap out (everything except the main board is user swapable) and eventually sent me a new main unit. No charges as long as I used their prepaid boxes to return the unit.
It is a great daily maintenance unit. Only real gotcha is that it can get caught up on some weird things like cords and furniture center stands. So you do need to think about how to make the area robot friendly. Also, things like paper and tissue are light enough for it to suck up but too big for it to handle. So you'll see tissue wrapped around a roller, pieces of paper with chewed up corners, etc. Also, if you have pets you do have to go dehair the unit from time to time. It is super simple, just pop off the front wheel remove the hair and pop it back on, and then open the roller assembly and do the same for the rollers.