Regarding the battery comment, actually the latest batteries for these units hold a ton of juice. The replacement battery I bought 6 months ago seems to run almost twice as long as the original. The only problem is that charging also takes a long time so if you have a giant house, it may still be running when you get home from work. Also these appear to be retrofitted units to fix the bearing issue they had with the original design. Thus there is a wide gap on the underside that is not touched by the brush.