There are plenty of good reasons to use Python 3, it is way more elegant and consistent. The way text and binary data is dealt with is incomparably better. I doubt that anyone who ever had done any serious coding in Python 2 escaped from the mindfuckery of mixing unicode and ascii.
The problem for a wider acceptance continues to be the libraries... for instance, Twisted. It is good that there is an async module in the standard library now, but too bad that my code already relies heavily on Twisted.
And about the GIL: if you are complaining about it, you most probably are not using the right language for the job.