Like MikeyAl, I enjoy the daily & weekly chores most of the time. It gives me time to observe things , spot a problem, think of a better way to do things. Now the heavy duty stuff like yearly maintenance is another thing .....
But I have an inherent liking for gadgets and tools that solve real problems in practical & innovative ways. This machine seems as if might wear out quickly and since its non essential could easily end up in the equipment box never to see the light of day again. Having it take up space on the glass is a good point as well. But I can see how in special situations like a hard to reach display aquarium in a resteraunt for example, this thing might be great. I could also see it being useful if it was efficient in keeping really huge aquariums clean. Especially when you have a case of paying for cleaning labor wages. Hard to justify for the average medium sized aquarium.
I run enough HC GFO now that I only get a light dusting on the glass every week or so. No big deal. But I do get coralline growth & can't see a robot doing a good job on that.