Yes, Julia is amazing! In the same time, if you want to write a package for Julia you _may_ need to use C/C++. D is going to have integration with Julia in 2016 ;)
Julia is really fast in 95% cases, but 5% still "make the weather". The pairwise summation is an example. I will post benchmarks D vs Julia next week ;)
I would say the biggest benefit of D is static typing. In Julia you can run a simulation and discover only after half an hour that you misspelled a function
D already have good integration with Python. You may want to read this article http://d.readthedocs.org/en/latest/examples.html#plotting-wi... (it may be a little bit outdated).