[spacedome]

I think the functionality of Julia's sparse arrays is mostly on par with scipy.sparse, it's just a bit rough around some edges still, and spread out into non-base packages (e.g. into IterativeSolvers.jl, ARPACK.jl, MUMPS(*).jl etc) of various maturity. Having the sparse arrays built-in might (hopefully) lead to a large ecosystem of interoperable sparse packages, but as with much of the Julia ecosystem this is still a work in progress.

Personally, working on sparse eigensolvers, my only complaint is that IterativeSolvers.jl is still somewhat lacking (though the ARPACK.jl bindings are more comparable to what scipy does), but otherwise cannot imagine going back to python for this kind of low-level numerical research. Having code run comparably to fortran speed (barring some memory annoyances) is huge for working on numerical algorithms.