I was super skeptical about getting a Roomba, but there was a great deal during around the holiday's last year, and we pulled the trigger.
I'm still 100% happy with the purchase. Does it vacuum as well as a person? No, absolutely not, but what it does do is remove 90%+ of the work.
My only suggestion is that you get one that has a self-emptying container. We have two kids and a cat, and we still only have to change the bag every few WEEKS.
I'm not going to tell you it's perfect. It will occasionally get stuck, or you have to clean it out, but boy has it removed a lot of work for my wife and I.