Debugger support is almost non-existent. Using Atom/Juno IDE is a D-grade experience. Julia offers little help to debug problems - errors are almost always without failure - completely tangent to what the real issue is.
Julia takes forever to start, syntax was wonderful pre 0.4 days, now the syntax just looks absolutely jarring to my eyes. Julia's speedups can be offset by using many many far better technologies - Numba, Numpy, Cython, PyPy etc.
Julia's ecosystem of libraries is a deserted land - that's expected for a new language. I hope it improves, but the core Julia experience needs to improve first.
On the other hand, I've been following Rust development and the developers made absolutely sure from the get-go to focus on debugging/errors that show what the actual problem is, provide a stack trace and figure out where the problem started. Julia absolutely sucks at this.