I personally find it quite ugly and clunky. I feel like the interface is optimized for children, and the number of ads you have to tap through to get even a modicum of knowledge is quite clunky. The last time I used it I spent over 20 hours to partially learn almost 4 letters of the Arabic alphabet — I’d call that pretty clunky.
Objectively they have a good team, but I do not think it’s above crticism in either regard.