So far, Elm feels like it is over-hyped. The UX just isn't there in my opinion. A few examples:

• The error messages are supposed to be so great. But they are really just overly verbose. And wrong often enough to drive me nuts e.g. I had a variable name typo, or a misplaced extraneous comma, but the error messages where about completely different things. And sometimes the error message doesn't even say a line number.
• The limitations of the error detection & messaging means that I end up breaking things apart more than I otherwise would, just to be able to get the compiler to tell me the real error.
• The debugging story is supposed to be so great, but I haven't seen a way to e.g. debug a single function interactively from the repl. Debugging utility functions seems to be only doable as part of an overall app being run and debugged?
• elm-format drives me nuts. I really do not like a lot of the aesthetic choices made there.
• As much as I love Haskell, I really do not like whitespace-sensitive syntax since it leaves too many things as ambiguous, which then makes using elm-format a gamble and a wrestling match.
• Seems like several elm editing modes think that format-on-save is enough, but I consider it necessary but hardly sufficient.
• The naming of things sucks now because of the history of change. Which linear-algebra package should I be using? Why did webgl fail to install? etc.
• The unit testing framework (uh, again, which one should I even be using?) elm-test doesn't support a message string per assertion to show when Expect fails, which makes it even more annoying to try to figure out why it failed (cf. the lame debugging story).