Head First: Python is a very easy to read fast introduction into python and its possible usages. From web to andorid applications, many things are covered.
The Head First approach is particulary valuable for a language like python, because of the huge variety of free online documentation it is pretty helpfull to get a rough clue of whats possible. It is not that important for the book, to be a complete reference, more it has to be and it is a highly usefull introduction and overview which is even interesting if you are already familiar with python.
Last but not least, the approach to cover only python3 seems to be a pretty good idea, because many programmers hasitate to upgrade.