I've got a Roomba, as above you do have to do a tidy , take out thin rugs, etc. and in the dining room put the chairs up on the table (it will go round them, just take longer). And yes you have to empty out it's little dustbin regularly, but at least that shows it's working. And pull fluff from the brush if you have a fluffy carpet.
On the other hand, call me lazy, but I find this way less tedious than actually doing the vacuuming (and anyway you have to pick stuff up of the floor for that too). It's good fun watching the little fella scoot about the place! I've always liked watching other people work.
In summary, it's like having a dishwasher instead of doing the washing up – yes you still have to load / unload, but it's definitely less work overall.
And besides – it's a robot! Doing the vacuuming! Like it's the 21st century or something!