I've had one about 5 years. A Neato Botvac D85
It was pretty expensive when I bought it (about £500), but is pretty old now and been surpassed by all the newer models.
Honestly, I've found it fantastic. I had 3 cats and a dog at the time, and the amount of hair they would drop daily was incredible. Gary (my robot hoover) would go out on his daily schedule and do the whole lower floor of my house.
It's not as good as say manually hoovering a room, but would say it's about 90% there. (bear in mind this is an older model). Easily good enough for if you have visitors coming over etc.
Positives+ Easily replaces daily hoovering
+ Naviation is really impressive, you think it's missed a spot but it always goes back to finish it off
+ Set it off and leave the house, come back to hoovered house
+ Set it to hoover 30 mins before you come home from work, always come back to a clean house
+ Cleaning upstairs is easy. Open all the doors, and then set him off in the hall way and he will hoover all 3 bedrooms bathroom etc
Negatives- They are expensive. I would avoid 'cheap' models as from looking at reviews you really do get what you pay for. The Cheaper models clean less and have more issue navigating.
- You have to empty to dust bin after every hoover. The new super expensive ones do this automatically but that comes at a premium
- If your pet has an accident, and then you hoover sets off on his journey you are in for a bad time. It happened to me once it reminded me of spreading marmite on toast.
- He can't do stairs, so you will still need to do that
- Over time Gary has got less reliable. His side brush broke (which I repaired) but one of his bumpers keeps sticking meaning I have to free him. To put it in perspecitve though I'va had him 5 years and use him every day, so he's hoovered my house approx. 2000 times.
- *Edit* - You do have to prepare the room. As in you can't leave cables/kids toys all over the place as they will get caught up in the brush. TBH I'm so used to that now that it didn't cross my mind to begin with.
When I was googling the picture I read a few reviews of people complaining about poor navigation. I can only vouch for my own experience and have had minimal issues. He sits in the kitchen below a shelving unit, and goes off into the hallway, livingroom and does under the dinner table with now issues and comes back to recharge himself (if he runs out of battery he will redock and then set off again when recharged).
I would absolutly recommend one, but only if you are prepared to spend a bit of money. I'm not convinced the £200 models are up to the task.