Question about Hutt DDC55

I bought the DDC55 mainly to clean the glass roof. It works, but it's a bit disorientated upside down, i.e. it doesn't clean in a controlled manner like it does on a vertical surface and it never reports that it's finished.
But if it cleans for long enough, it gets everywhere. For me it's ok, much easier than cleaning by hand.

I sent it back a long time ago. At first I was totally thrilled, but the window robot leaves a lot of streaks and it looks almost worse after cleaning, so I wouldn't recommend it at all.