It seems like Roomba is one of those super divisive items on the MMM forums, lol. Some find it matches their values for cleanliness, freedom, time, etc, and others find it irritating to use and/or a cost that could easily be avoided by using cheaper tools, time, overcoming a desire for specific levels of cleanliness, etc.
I obviously fall into the first camp :)
Two more favourite things about it:
1. I have an intense shoulder injury -the result of vacuuming lots and scrubbing tubs (I was a home support worker) in the months following a bad bicycling accident (cycling to one of said clients' homes). Many years later, the ONLY effect of the accident is strong pain in the shoulder upon lots of vacuuming. Roomba eliminated this. (I don't have or use a regular vacuum anywhere. I don't have stairs, and Roomba does hard surfaces, carpets, area rugs, etc, without my involvement.)
2. Because of point #1, as well as an aversion to noise, before Roomba I swept all my floors and carpets. The stiff corn broom did a good job. However, I also have an absolute aversion to feeling stuff via the soles of my feet -crumbs, little bits that I may not even notice visually but which trigger Aspie/sensory stress. My kid and I are both naturally very neat -no food droppings, etc- but these tiny bits aggravate me. Roomba eliminated this, and works (makes sound) while I'm out of the house. I know I could have changed other habits -start wearing my shoes indoors (which I think tracks in more dirt), or wearing slippers, etc, and continued sweeping, but Roomba resolves so many needs, it seems a perfect fit for us. In fact, it's one of the few things that made the cut when we last moved and everything we owned needed to fit inside our compact car with us!
If I were even wealthier, I would buy one for at least three other people I know, who struggle with floor stuff and/or vacuuming for one reason or another.
The only place I have missed having a regular vacuum (which, again, I gave up years before Roomba came into my life) was when I was shrink-packing for my last move. I borrowed a vacuum to draw the air out of four bags. I can't justify owning a regular vacuum for that :)