1. The language version starts with 0, i.e. it is being clearly communicated that there is no guarantee of stability
2. The language development is being run by an opinionated BDFL who likes to take his time to think through new features. There's more of novel, well-thought-out ways of doing things, but less support for "I need this for my production use case now"
Neither of those points is inherently bad, but if you plan to adopt Elm in your product or codebase be prepared to rely only on the feature set you get from current version. Expect breaking changes in the future when new version drops.
There's lot to like about the language and it can be a good introduction to functional programming if you are not yet familiar. IMO it is definitely worth spending time on to improve your skillset and to gain new perspectives on programming.