One problem that I have with Plex is that it usually fails to properly load when it loads on Windows boot-up. The thing is... the program does load, but even though it says you connected to Plex as <username>, none of the libraries work. The recently added and on deck items don't show up, and clicking on the library name does nothing. I have to close out the program and relaunch it. I think it has something to do with the network connection not being active when Plex starts loading.
If you need a way to catalog your movies, it works pretty well. I just scan the barcodes via my phone's camera, and it adds them to my collection. It handles releases from many regions as well, which is nice since I sometimes pick up region-free releases from Amazon UK.
I have plex installed but I rarely use it. I guess I'm just obsessed with having everything installed. I use these, in this order: WMC, Media Browser, Kodi, and Plex. I personally don't care for the simplicity of the Plex interface. I need more eye candy!
Have you tried the Plex Aeon skin? The default Plex skin is pretty dull, but Plex Aeon is all purdy. My only complaint is that the latest version of Plex Aeon seems to have removed the pop-up context menu. Since I have the NUC sound drop issue, I used to use that menu for restarting the machine.
Personally, I just run Plex to get to my collection outside of my home network. Inside I run myMediaPC, from the PlayOn people, and use the myMedia app for my Roku's. The server does all the transcoding, filebot does the naming for me, and it just works.