I think my Roomba was the best purcahse I ever made. We have a mix of ceramic tile, hardwood floors and carpet along with a long hair cat, 2 Pomeranians and a Miniature Pinscher. The hairballs tend to accumulate under the china cabinets because as you walk around the breeze from your feet blows the hair one at a time under the cabinets.
The Roomba goes under the cabinets and gets all the fur. It goes under tables chairs and goes along the walls until it comes to a corner and then does a tight turn around the corner. It cuts down on all the dust and allergens in the air. I just tap my toe on the start button before I leave for work, it spends a couple of hours cleaning and when it gets tired, it parks itself back on the charger.
I purchased mine from http://www.woot.com/. WOOT has some really awesome deals. The Roomba’s are usually refurbished from the factory, but come with all applicable warranties. WOOT tends to have the Roomba every 4-6 weeks and is worth checking in everyday to get one.