In today's episode of PhiMarHal discovers things 10 years after everyone else, I've been enjoying Duolingo lately.

They got the visual and sound design right, the gameplay loop is tight, you stay on the treadmill painlessly.

Oh, and it's fluid on my mid-range phone (so many apps fail this part).

The most common criticism I've read is that it doesn't scale beyond teaching some vocabulary. I guess I have to go further and see. 

As someone for whom vocabulary is always the prime obstacle while grammar can be inferred, the value is fantastic in any case. It solves the cold start problem.

It's interesting to see how language apps like Duolingo leverage engaging design to enhance learning experiences. Just like in crypto, user experience can make or break adoption. Continuous improvement is key, especially as users crave deeper knowledge beyond basics.