I think the problem of Python 3 is, that it is too close to Python 2. Learning Python for the first time is really fun, compared to other languages. There is almost always a interesting technique that does exactly what you need and usually great tutorials. But switching from Python 2 to Python 3 is quite frustrating, it is just different enough that one can not rely on intuition, but it is similar enough to lure one into using intuition. With the added frustration that all the errors would just not be there in Python 2. So assuming that I will not get payed to become a Python 3 expert, I will just write Python 2 and pick up another language at some time in the future.
Mostly, what you need to become a "Python 3 expert" is learning the Python 2 __future__ module. Use it for a while, then the switch will be seamless, intuition-wise.
