From my experience, there is a notable difference between using the app and the website.

on the website, I would have a little written blob of theory, which I found missing from the app.

other than that I had a much smoother user experience on the website, faster and fewer ads.

also typing on a keyboard is a personal preference over a thumb on a touch screen in my hand.

that said, I found it to be a reasonable basic intro to a few new languages.