Python has great libraries and is easy to read and write.  

When I write it my code is briefer and less buggy.  Meta-programming tricks with generators (that I am just discovering) mean you can write libraries with less verbiage.

Over the years it has attracted an interesting crowd of people who do interesting things with it, making learning it a continuous education.

That said, I wouldn't write an OMS in it.

Python is a very good glue language and is available on many platforms, NumPy is a very good library for anyone doing financial calculations.