Gael puts in a plea for backward compatibility; I totally agree. Numpy sometimes goes out of its way to make this hard. For example, when the syntax of histogram were changed you got a nice DepreciationWarning about an option to switch to the new behaviour; great. But a few releases later that option went away and code carefully written to survive the transition stopped working; that didn't make me a happy user. R

Also, putting more emphasis on backward compatibility is possible. For instance, the 'order' parameter added to np.copy could have defaulted to the old behavior, 'K', for a year, with a DeprecationWarning, same thing for the casting rules.