It's pretty easy and straight forward, the login UI is similar to netflix where you can have profiles per user and have them shown on the login screen, etc. They get placed straight into the view of your library, from there they can simply click play.

I'm not up to speed on transcoding, but I do notice my web users always have to transcode, assuming due to their native browser playback support for codecs. Local installs of the Jellyfin player seem to avoid this on most systems.