We just got a Neato XV-21: http://www.amazon.com/Neato-XV-21-Allergy-Automatic-Cleaner/dp/B007JOJ9QQ/ref=sr_1_3?ie=UTF8&qid=1404627581&sr=8-3&keywords=neato+xv
Had it for about 2 weeks and I'm surprised by how good it is. I had doubts about it doing the whole house (about 28 squares) but it does. Does one area and when it's going flat returns to the base station, charges and then sets off from where it was again. Gets up and down little lips and over raised rugs no problems and dust bin is a reasonable size.
It won't replace a manual vac but
it means we can go heaps longer between manually vacuuming.
Takes about 3-4 charges to clean entire house: about 1/2 a day - means you sort have to run it when you're not home (but it can be programmed to run at certain times) or it can get under your feet.
It's gotten "lost" once and couldn't find its way back to charger.
Overall I'm really happy we have it and -keeping the above in mind- I would recommend getting one or something like it.