Manjaro Capella has matured too stable. As far as I can tell; it has been stable for a long time - but now it is official. This should make it a reliable alternative for most computers.
Many come to Manjaro from Ubuntu.. and they love it. It has become a user friendly distro even if it is Arch based. There is a market for a user friendly Arch as Manjaro has proven.
Manjaro is not just an Arch derivative since it brings new features to the table; like the unique Kernel handling and also givers back polished software to Arch like Octopi and the Whisker menu with its splendid translations and Compiz.
Compiz is not dead and maintained by Manjaro devs; it is totally usable on Arch too.
If you gofor for the Manjaro version (compiz-manjaro) ; it is rock solid and stable (but no cube). If you go for the trad. version you get the cube and can play a lot but it is not that stable.
I find the Manjaro version just fine as it does not get in your way, but still has all the whistles and blows that you occasionally may need.
Manjaro has worked a lot with Kde lately and ti comes with Plasma 5. I use Xfce4 or Openbox and I am perfectly happy with that.
The Openrc version without systemd is extremely fast and really a perfect option for older hardware (and new one...) Try it... you will be amazed.
Manjaro is probably the distro with the most flavors, so there is something for every taste there.
..And the Arch Pacman package handler is still the best in the world.