3.4. gave a good virtualenv by default. That helps a lot

I still use normal virtualenv, what am I missing by not using pyenv?

3.4 gave us pip installed by default https://docs.python.org/3/library/venv.html

Before that it would give you an empty venv, not even setuptools

Yes, you can use the Python 2 virtualenv on Py 3 but I remember that there were some problems

The usage is essentially the same, just a different command. Huge benefit though is that if you have Python 3.4+ installed you already have the virtual env and pip installed, so things are much simpler.

Which one is that? I'm not aware of it.

    python -m venv

I'm not sure what the differences are to old virtualenv, but the biggest feature is that it works out of the box as long as you have Python > 3.4. No more googling "how to install virtualenv" or "easy_install pip; pip install virtualenv" stuff.

Unless you're on Ubuntu, where they ship a non-functional version of venv and require you to "sudo apt install" python-venv to get the working version, defeating the entire point of a simple module in the stdlib that lets you manage your Python environment as a user.

The big improvement on 16.04 is at least the error message explains what's going on.

The venv module in the stdlib: https://docs.python.org/3/library/venv.html#module-venv

in addition to what other wrote you also have pyvenv command which is much convenient way of using it in cli (the usage is same as of virtualenv).