[resc1440]

Mitsuhiko has written extensively about Py3 unicode problems, e.g. http://lucumr.pocoo.org/2014/5/12/everything-about-unicode/

I think a lot of it boils down to, sometimes you really really don't want to care about unicode. Linux filenames are one thorny issue - Linux thinks of them as strings of bytes, and a tool is broken if it can't also deal with them that way. Py3 makes it very difficult to do that correctly. There are also issues with stdin/out being opened as unicode vs byte streams.

For web development, the "unicode sandwich" (http://nedbatchelder.com/text/unipain.html) works great in my experience. However, I can see his point that for some kinds of tasks, Py3 is unambiguously a downgrade.