I tried Jellycon briefly when I started but it's unfortunate that it doesn't integrate into the Kodi UI properly, so there's no way to really use the Kodi interface nicely without casting from the Jellyfin app. It more or less just becomes a playback client for the Jellyfin app. If the Jellyfin app wouldn't be such a disaster when casting I probably would be fine with that.
Might try it again in the future but the Jellyfin app experience is nothing like what Kore or Yatse can do directly with Kodi.
I thought so too. It doesn't have enough options for power users and too many for newcomers. It caters to a middleground that barely exists.
The codecs are also the #1 thing that annoy me in Fedora. Because of shitty US patent laws the rest of the world has to suffer.