My startup uses Phoenix, along with a Vue front-end. The combo is an absolute joy to use. The benefit that has had the most business impact for us so far is developer productivity. A couple of months ago we met with a prospective client to discuss their use cases and conduct requirements gathering. They really liked what we showed them, but the CFO wanted a dashboard that displayed the data in the app in a specific w…
I'm also doing an startup -- we've been working on the product for only two weeks and we just released access for our first pilot customer, with an initial feature set we are very happy with. Apart from the productivity, it's been a long time since I loved programming. Keep in mind I was doing embedded C development for a few years, so my web-fu is a bit rusty lately.
The only thing I miss sometimes is types, especially when refactoring. Java with IntelliJ will spoil you, I guess. I was thinking about going with Kotlin because of this, but I was really digging the Phoenix project structure and I love Ecto.
All in all, a great experience.