Seems to run well, but has a very high-pitched squeal as it runs. Our downstairs Roomba i6 series does not make this noise. Possibly why it was returned. Only downside (apart from the noise) is the "dust bin full" sensor comes on a lot - even when the bin is empty. It seems to get dirt on the sensors frequently. So far, just wiping off the sensors seems to work so not a big deal at this time. Happy purchase.