So to sum up the Mageia 4 experience then:
It works well out of the box with KDE. For that it can be recommended to newcomers to Linux.
It has a new nice welcome that will get every (KDE user) started:

KDE will work just fine.
If you need a lean slim machine and want to implement Openbox; it cannot be recommended. Mageia is trailing distros like Openmandriva and Manjaro by a mile there and lack even basic packages to make it work "properly".
It actually does work but you have to do some somersaults to get there. You will notice the differences when checking out the wikis:
https://wiki.openmandriva.org/en/Openboxhttps://wiki.mageia.org/en/Openbox I have written both - and tested that they both do work. It simply is easier to implement Openbox in Openmandriva, and the result is way better too.
Mageia 4 can probably live with that since newcomers do not start with Openbox anyway, but they will have to accept that they are taking the back seat here.
And I am not a newcomer but the process of finding out how to set up Openbox frustrated the hell out of me in Mageia 4.
(My research is in the Wiki so it should be easier now).
Also my humble (Berserk) requests to improve the Mageia Openbox experience in Bugzilla have been closed as wontfix at some point because there was a "better" solution.
So my attempts to contribute have been rather put off. In Openmandriva I the bugs I reported and software requests all were fixed within 24 h by my favorite guru (crisb) over there.
And they have a great Openbox to show for it (in all modesty

)
Mageia 4 is good with KDE. According to jkerr it is good with xfce4. It is bad with WM's like e17 and Openbox.
(I had to install mate-polkit to get the admin prompt - in order to fire drakconf etc.)
I have not set up a LAMP server in Mageia 4 but I will anticipate that it is as good as Mageia 3 was - which was very good.
So there you have my experience with Mageia 4.
If I will use it now?
Nope
It has no rolling release ( I try to avoid installing every 6 months) and lacks the flexibility of Manjaro which is also newbie friendly.
I did install Mageia on my old mothers lap though so I have to stay updated
