I've got roomba 400 as a Xmas present. It is perfect when it works. It did a great job cleaning under a king size bed and sofa. I used it twice a week on each floor. It started having a problem three month later with wheel/front sensor just three days affter the last date for store return. Called customer service, they adviced to clean it with dust buster and reset it, but the problem persists. One month passed in communication with customer service, roomba is not working properly. I have dust bunnies under my king size bed. I will return it eventually and get my money back, then get old style...