For me, it runs without an app and does its job well. I probably can't use all the functions, but I don't care.

Same as the previous answer. For example, you can choose the amount of water used. This option is not available without the app. In my house it stopped working. I couldn't work out why. I waited for the battery to discharge, then charged it again. It's working again. Maybe with the app I would have known what the problem was.
It does the job but it's clearly not up to the standard of other manufacturers. But for the price....