cjbrambo, Elena ``of Valhalla'', Kevin Ford, Mike Linksvayer likes this.
Very nice experience for now, using Plasma. Thanks @JanKusanagi for being my handy help-desk support in "how do I...?" "Where is...?" etc questions.
I have got accostumed very quickly, and the computer seems more agile with this desktop. So, I'm staying for now (husband laptop at home still uses GNOME, and my laptop, XFCE. We'll see in some months how this evolves).
I have discovered that my problems (artifacts, icon, window titles corruption, freezes) were not strictly related to gnome-shell. In Plasma, I have tuned the desktop effects to keep only the ones that I want (very few, but still), and after some hours of using the computer, I got black boxes instead of context menus, some freezes when changing windows or launching a panel, and so. It's great that, when this happens, I can quickly disable all the desktop effects with Alt+Shift+F12 and then I can go on working. But if I re-enable the desktop effects (pressing Alt+Shift+F12 again), The screen is frozen, I can move the mouse but I cannot switch windows (even with Alt+Tab) nor click anywhere.
So, the conclusion is that something is wrong maybe with my VGA card driver or with xserver-xorg-video-intel or maybe I have to resign and not use desktop effects at all. I don't know. I'll research a bit more and then write my blogpost about the migration to Jessie of this PC (including migration from GNOME to Plasma).