I bought an iRobot Roomba Vacuum Pro Elite a couple of days ago and I have to say, so far it's exceeded my expectations. The thing is a champ at cleaning carpets and hardwood floors, and the geek side of me gets to stand around and watch it learn what a coffee table leg is and encircle it.
While I don't have to do the actual vacuuming anymore, it takes longer to complete the job. The robot spends some time back-tracking and repeating areas. And before I can even start I have to complete clear the room of cords and stray items, something I could do on the fly while vacuuming before.
In 3 years I will probably look back on today and laugh that I woke up at 7am so I could vacuum my living room.