Question: does the tevaplanter actually work?

I’ve been crawling many forums etc., and it seems to me in most cases there is little to no success in actually maintaining a healthy plant on the tevaplanter. Still, quantitative reviews are overwhelmingly positive. This confuses me.

I have been given a gift card to buy one as I’ve wanted one for ages, but have been stalling my purchase as I don’t want another useless gadget hanging around my home.

What is your experience? Can a plant be sustained long-term on the tevaplanter? And how much harder is it than simply growing it in a pot?