I love but it was not from the beginning!

This smartphone is really fantastic. Very bright, fluid, excellent sensors, options galore, S Pen madness (from Note 1 Note 3 to the superior quality is striking). It is beautiful, and very pleasant to use.

However beware, the beginnings were atrocious, and because of the version provided firmware (Android 4.3 etc). Indeed, it was subjected to constant disconnections of the SIM card and thus of telephone networks (voice and 4G). Kies is always bad, even in the version 3, impossible to update via the computer.
So if you have this problem ("SIM card removed, please restart your phone"), turn on WiFi and update the firmware by this route. This is how I fixed the problem.