It came preinstalled with some Python 3.8 venv. The venv was put into the Git repo root directory, which is a bit strange, as I first needed to modify my gitignore to ignore that.
Git push directly from the VSCode menu directly worked and pushed the change back to GitHub, without further setup.
I did not expect that I get a full virtual machine, but it seems so. I edited some Latex project, and pdflatex was missing, so I did `sudo apt install texlive-full`, it installed 4GB of packages, and then all worked fine.
I also edited some TensorFlow stuff, and `pip3 install tensorflow` also just worked.
The side preview (eg. for markdown or Latex) somehow is broken. It stays blank. However, e.g. you can open the Latex PDF preview in a new browser window, which works.
The speed just felt native. There was no latency. It feels exactly like native VSCode.
I very much like it. I guess the side preview will get fixed soon. I will probably use it for a couple of smaller projects, of different kinds, like Latex, Markdown notes, smaller Python stuff, or other smaller code projects where VSCode is fine.
Otherwise, for e.g. Python, I still prefer PyCharm, which has far superior code browsing and auto-completion. Codespaces with PyCharm would be really nice! Or maybe VSCode can improve on that. Or maybe VSCode can even reuse the language server from VSCode. Or at least the inspections. I think this part is open source, right?