Cities: Skylines - Content Creator Pack: Train Stations Review (BlueBushBoi)
A good DLC; one of my favourites. The assets are highly detailed and I've never experienced functionality issues with any of the stations. It has brought some of my favourite assets to the game, and is excellent for vanilla playthroughs.
For modders, note that these assets are very picky detail-wise about connecting to non-vanilla networks. Oftentimes they will not make the correct railway connections: for instance, connecting the quad-metro track to the dual-island sunken metro station will not work consistently without TM:PE, and even then the actual visuals for the rails will not work properly. The only station from the pack that functions correctly with larger rail networks is the ground level express bypass train station, which can connect to BadPeanut's 4-rail network, but only with Advanced Node Controller (setting the connecting node to middle) and TM:PE lane control.
Overall an excellent DLC for vanilla, with a few nitpicks for detail-obsessed modders like myself.