Is python 3.4 backward compatible with python 3.3?

Question

Assuming that somebody's concerned only about packages and codes that already work under python 3.3, can they migrate safely to 3.4 without worrying about backward incompatibilities?

This is concerning me because I have to setup a development environment compiling all the sources from scratch, but I'm not sure if it's ok to directly jump into having 3.4 as the only option (assuming 3.3 used to be the only option).

Answer 1

For almost everything it will be compatible...

http://docs.python.org/3/whatsnew/3.4.html

but look at deprecated, removed and specially Porting to Python 3.4 section