I have an old Roomba from iRobot (at 400€ back then a "cheap device" according to DerBjoern), which manages to clean an entire floor with children's room/playroom etc. using the random principle. Apart from only having to personally reach inaccessible spots every few weeks, I find it quite decent, since in addition to the children there are also 2 cats with very fine hair causing mischief (the doors are basically always open). The vacuum robot is quite robust when it comes to objects lying on the floor, cat toy ribbons, and other obstacles. Definitely more robust than the Vorwerk VR200, which is now responsible for the ground floor at our place. However, it handles the complicated geometry there better than the Roomba (e.g. kitchen island and other common trouble spots, there the random principle was sometimes unfavorable and the Roomba did not manage to clean everything with one battery charge), it covers the rooms very systematically. On the other hand, the Vorwerk struggles more with objects on the floor. Despite its supposedly higher "intelligence" and more sensors, it sometimes navigates around toys in a very odd (and time-consuming) way and, for example, has problems with our cantilever chairs and office chairs; this has improved a bit with a third-party attachment, so it now also blocks earlier on lower obstacles. At one spot we have a magnetic strip, which it still ignores every 6th time. The suction power of the Vorwerk seems somewhat better, but both vacuum robots clean equally effectively. Both devices are actually easy to clean/maintain and empty. However, with the Vorwerk, the filter quickly clogs with cat hair in our case, and a fine-mesh screen in front of it very effectively prevents cleaning. I have now bought a filter with a larger mesh from a third party (but have not tested it yet). Otherwise, I have to tinker a bit because I don’t want to buy new ones every month.