Where is the power off in Gnome 3?

I recently installed Gnome 3 and I must say that in my old machine, it runs significantly better than Unity. Indeed, I wasn’t able to run Unity smoothly.

But there are things in Gnome 3 (and in Unity) that I’ve not accustomed.

For instance, there is no power off button in Gnome 3 user’s menu…

That’s false. Simply it’s hidden. You can show this option hitting the Alt key while showing the user menu.

There are some more tweaks, it’s better to run this cheatsheet and you’ll feel more comfortable with Gnome 3:

https://live.gnome.org/GnomeShell/CheatSheet