We have been using for about 3 years now. Myself and the two other devs enjoy working in it more than the other languages we use (Ruby, Go and vanilla JS).

Upgrades have been pretty painless, and each new release brings a new level of ease of use.

We have made some architectural mistakes as we have learned the language. And since it is a newer language there are not as many established conventions for code organization – but we are figuring out.