However, there's the debugger issue. There are several debugger alternatives. It's tough to figure out which debugger is canonical (or is any of them the canonical debugger?). The one that seems to being used most at this point is Debugger.jl. However, it's exceedingly slow if you're debugging sizeable operations (matrix multiplies, for example) - I'm talking hitting 'n' to step to the next line and then waiting several minutes for it to get there. There's also Rebugger.jl, MagneticReadHead.jl (IIRC) and Infiltrator.jl among others. I finally found that Infiltrator.jl was a lot faster for that machine learning program I was trying to debug, but it's rather limited in features (the only way to set breakpoints it seems is by editing your source, for example).
And this isn't the only case where there are multiple packages for achieving some task and you're not quite sure which one is the one that's the most usable. I think what the Julia community needs to do is maybe add some kind of rating system for packages so you can see which packages have the highest rating.