[abolibibelot]

In terms of threading, Ruby and Python are in the same, sad, GIL boat. The speed issue is the same, but the C libraries alleviate this somewhat (Numpy, scikit-learn and lxml come to mind). Tail recursion is really needed when you have a functional language, and since Guido van Rossum, and therefore Python, has a bias against FP, the lack of TCO is not that glaring when you write pythonic code (which is kind of a circular argument, I know). When it comes to libraries, the old "batteries included" argument gets old, and the standard library shows its age, but it's usually addressed in external libraries... ...which brings me to my real gripe about Python, the ever changing way you're supposed to manage packages (use easy_install, wait, no use pip and virtualenv, wait you should take a look at wheels too, and so on).