I have one and it's 5 years old. I'm in the process of rebuilding the battery pack so it can keep on doing its thing. I learned that there is wide differences so do your research for a good one.
Who wants to come to my house and hack my Roomba? Kinda like worrying about someone coming to your neighborhood and brute-forcing his/her way into your wifi. Possible? Sure! Probably - Not even close!
Mine is still running after 5 years. A cell in the battery pack died and I got a replacement for $2.75 Just need to solder into the battery pack and it's back up and running. Ours runs daily and cleans about 800sqft on the floor it's on. Once a month I take it upstairs and let it go under the beds for the dust-bunnies.