I actually picked up a 400 yesterday at Target for $65. Was VERY disappointed. Charged it overnight last night and tried it in our living room/kitchen this morning. Neither rooms are large and the box even says it cleans two adjacent rooms. It basically ran around for 30 minutes (maybe), got some interesting spots under tables and chairs and behind the couch, but totally missed the middle of the living room floor. Then it ran up on something and started beeping. I thought it may be because it was stuck, so I put it down in an open area and tried turning it on again and it started beeping again. I assumed that the battery was low and it had to be charged. I packed it back up and will be bringing it back to Target today. A nice idea, and a great price, but really poor performance IMO. It may be better to purchase the $199 model they had marked down to $99.