I was hoping you would say the Roomba is great. I want one, but the cost would be a stretch for us now. I have hinted for one several times, but intend to really bug Santa about it this year. Usually it is not a good idea to give appliances, but this sounds like it would make my life easier. Always a good thing.
Amazon often has good deals on reconditioned roombas in their outlet:
http://www.amazon.com/s/ref=nb_ss_k/002-9352899-2591243?url=search-alias%3Dgarden&field-keywords=roomba
Just make sure you get the one that plugs itself in to recharge. It's worth the extra money.
Warehouse stores will also often have them on sale.