I've written a fair amount of Elm, and I still find it awkward. One issue is that I feel like I end up having to go back and add in brackets more than I would with the C-style syntax. I'm not sure if that's just the way I think thanks to being used to that, or an inherent problem.
The main issue really is that I think it's harder to read, as it's less clear what is being used where. The explicitness of the C-style makes it easier to see what goes where.