I decided to buy for a long time (the price is impressive), in the end I do not regret it. It is convenient to use, it washes quite cleanly, during the cleaning, a stepladder was never needed, which makes the process safe. What interested you when choosing: round or square? After reading the reviews, I realized that the corners do not wash both devices, but the square ones are designed for a large glass area. Round is more manoeuvrable. Will the robot fall from thick double-glazed windows? It is attached securely, in case of a power outage there is a battery, they promise that it will hang for 20 minutes on them. It does not depend on the thickness of the glass (unlike magnetic brushes), it can wash both bathroom tiles and mirrors. Which one to choose: 188 or 198 trunk? The 198th is more powerful, although I think that I would not notice much difference between the devices. Conclusion: Recommended!