An interesting robot: before buying, I read and viewed a lot of rave reviews and no less devastating reports of multiple errors, "factory marriage", etc. Realizing that the iRobot brand did not appear on the market yesterday and not all people know how to operate the equipment, I decided to take a chance . My impressions of using this home assistant are as follows: errors (like "31") sometimes happen, BUT, an analysis of the reasons for their occurrence convinced me that they arise not because of a "factory defect" but because of the peculiarities of the functioning of the orientation system when using Wi-Fi and the Internet. I noticed that from time to time the robot slows down, the blue backlight on the lid starts to "run", then it confidently moves on. I believe that the positioning system refers to American servers, processes something in the clouds and pumps it back out. So, if even with a "good" Internet access to their servers is "not very" it can "glitch" . That is, in my practice of using the vast majority of days of cleaning the entire apartment without errors (several days in a row), but there are also days when errors appeared several times (2-3) in one cleaning?! But there is no trend towards the progression of "buggy", on the contrary, the complete absence of the system! I didn’t use the vacuum cleaner at night, so I can’t evaluate its ability to navigate in the dark. In general, I like the S9 + and I don’t regret the money spent on it. The wife, initially very skeptical about the Roomba S9 +, admitted that it cleans very cleanly and if there is a pet, such a device is simply necessary, now she is also joining the use of robotics.