I have a decent roomba, reasonably new, and love it. I bought it to help kickstart a wootoff, and to give to my wife. The trick is to use it frequently, like every single day. Give the place a really thorough clean, then schedule it to run every day and it will happily maintain that level of clean. Just empty it out every night. You do have to keep stuff off the floor, of course, but that's not too bad. You end up spending 5-10 minutes a day, and having a clean place all the time.
If you're observant of routine, I'd say go for it.