Too many high profile community members basically saying that it's impossible to work with the core team on improvements, with no clear communication that there even is a core team left any more, and bugs in the standard library/compiler that haven't gone fixed despite being one line changes. Many, many pull requests with such fixes have gone ignored for 3+ years. No indication of any possibility for a superior FFI or at least a path forward for the evolution of the current one.

The language itself is still mostly fine, so long as you don't run into its limitations. I still wouldn't recommend it going forward for the above reasons, though. Too many warning signs and contributor goodwill unnecessarily burnt. Evan is a perfectionist and clearly has no interest in developing a feature if he can't see the use case for it (his response to negative numbers in case..of expressions was a classic example).

Personally I think it's all a bit of a shame, Elm is one of my favourite things ever in web development. I really, really wanted/want it or something similar to succeed in terms of major projects being written in it.