I'm with you. I considered a Roomba a few years back but came to the conclusion that a Dyson cordless vac essentially solved my problem by making it trivial to spend a few minutes pulling out and running a vac as opposed to hauling out a canister vac between housecleanings.
My brother, on the other hand, has dogs and has a newly constructed single level house that they keep pretty free of clutter. A robo-vacuum works pretty well for them.