I have a complete different experience. Went from cheap robot to high end dyson standing vacuum cleaner, and the latter performs much better. Robot was getting stuck everywhere, after some time the mechanism broke due to dust getting inside the gears. Now i just spent 10 minutes every two days for a quick vacuuming around the house and lo and behold - the dust is no more.

It might just be that the robots aren't best suited for small flats.