This, + general storyline and execution of the product made it the first game I found myself to be really involved emotionally with. Say, when I picked up the second game and met an important NPC from the first, I literally felt like I've just rejoined with an old friend. By the third game I actually printed out a photo of my character and her entire team. It's crazy how deep a good video game can touch you.
Oh, and I spent 10-15 minutes thinking heavily about morality and consequences just to choose the right ending...
As for romantic subplots - they are very good and the game will totally hijack your emotions through them.
Not sure if it's considered a spoiler at this point but there's basically the one option to return a beloved companion to life (after recently being forced to suffer his death in the game). It wasn't necessarily the most logical choice nor is it the "smart" choice if you're treating it solely as a game and trying to get the most points/gold/etc....
...but when I was offered that choice there was not a single question which one I would pick. It's all just pixels and textures and sound effects but the chance to return a character that had followed you for most of the game hit me way harder than I might have expected. Manipulative,cheap, emotional exploitation? Maybe. No regrets though.
I just started playing The Walking Dead. In one scene, after another character saved Clementine from a zombie before I could, the game said, "Clementine remembers that you didn't save her." A very different feeling than failing and having to replay from a checkpoint.