it won't replace the main vacuum, but you can run it more often a spread out the regular vacuuming a bit.
the main reason I picked the discovery model is the remote for it. now I don't have to worry about a call from her being injured trying to move beds to vacuum under them (which she does a couple times a week). now she just uses the remote to drive it under the bed and chooses the spot clean setting (it just goes in an expanding spiral in this setting). it even has an optical dirt sensor, so if it hits a patch with too much dirt for one pass it starts beeping a bit and a little blue light flashing as it takes a U-turn and keeps vacuuming that area until it's clean. when the battery gets low or the room is clean it then locates it's base station and returns to recharge.
it won't fall down stairs, and it comes with a couple 'virtual walls' that provide a barrier to keep it out of areas where it could get broke or tip over fragile things and break them.
there's another brand that goes for about $1,300, that has some nice features. it also does the return to docking station but it's docking station also has a large vacuum built in so it empties the robots dustbin @ the base station. it has enough power to do deep shag as well. and you can program it to 'remember' the layout and clean different rooms on schedule ( you have to tell the IRobot version to begin, either with the buttons on the unit or the remote). with the self emptying and charging, you could set it up and it would keep the vacuuming done while you are away. it's a bit bigger than the iRobot model so can't go under as tight of an area but it does have a few limit switches mounted on top so instead of getting stuck it just runs in revers for a few feet and sets a new heading if the switches are tripped. a lot of cool additional features but $1,300 for a vacuum is a bit steep for me.
the iRobot rumba discovery is only about $230. I got a bit better deal than that on my moms. I ran into a guy carrying one into a pawnshop and gave him $50 for it, still brand new with all the paperwork and just missing the box.
it won't do deep shag, and cords on the ground and fringe on throw-rugs mess it up a bit too
btw- if you're one of those people who has to have all of the vacuum tracks lined up parallel in the carpet, you won't like this machine.
