Jellyfin is awesome. The DLNA support enables streaming to my local TVs without having to install apps on the TVs themselves, though I haven't heavily tested it with video yet (works great with music). Also the visibility of libraries can be managed per account, so not everyone you give a login to has to see all your content.
I have a decent size library and accessing Jellyfin via DLNA from a PS4 was unworkable for me. There is no search, and I couldn't find any way to select specific movies other than scrolling through the entire library by title name, or finnicky categories like genre or release year. Plex's DLNA implementation provides a "By First Letter" listing so you can find it via "By First Letter > M > (scroll down past a dozen entries to 'The Matrix')" instead of "By Title > (scroll down past a few hundred entries to 'The Matrix')". I don't think I'd be able to stomach that amount of scrolling to watch "Zardoz" on Jellyfin.
The way I do it is search for the media on my phone using the Jellyfin app, and the app has an option to cast it to whatever detected device via DLNA. You can do this from the phone app or web browser on your LAN.
You do have to have your media metadata correct though, e.g. ID3 tags, etc.
The Roku app is tolerable (so, about as good as anything not from one of the companies that's big enough to gain access to the lower-level SDK)
The Android app works really well on a Shield, and is much more pleasant to use. Can't vouch for other devices, and Android experience, especially Android TV, can vary a lot with the device. The Shield also handles more video codecs and can pass through more audio formats than my Roku can, which means less transcoding, which means my poor, weak old server doesn't get abused while still only barely managing to generate a slideshow. In fact, I'm not sure I have any files that the Shield can't handle natively.
I love, love, love having a Web interface to use when I want to change things. Mixing the library & settings management interface with the "6-foot" remote-friendly interface, as on Kodi/XBMC, is a UI disaster. It's also very nice as a fallback streaming option, and works way better than I'd have expected.
