Python 3 introduced many useful features that are not backward compatible with Python 2.x. It also removed numerous Python 2.x features that were maintained for backward compatibility, making Python 3 easier to learn and use and more consistent with the rest of the language. Our experience using Python 3 in domains such as machine learning and web application development shows that both the language and most of its supporting libraries have matured for adoption. We were able to fork and patch minor issues of existing libraries or avoided using incompatible Python 2.x libraries that had been abandoned. If you are developing in Python we strongly encourage you to use Python 3.
Python 3 was a major change from the previous Python 2.x that introduced backwards incompatible changes. It was notable for actually removing languages features, making Python 3 easier to use and more consistent without reducing its power. This has led to problems in adoption as some widely used supporting libraries have not been ported, and Python developers often have to find new ways of doing things. Nonetheless the drive towards making a language simpler is to be applauded, and if you are actively developing in Python, then give Python 3 another look.