Leliana is so much more than what we know.
What this DLC does is add a great amount of breadth and depth to Leliana. It totally changed the way I viewed her. The back story tell us of how once she was different and seeing that different Leliana and actually being able to play as her is a priceless experience. All of a sudden after playing this DLC I feel a lot more strongly about the quest to get rid of Marjolaine in Origins.
Basically what I'm trying to say is that this DLC is awesome. The musics is good, the story is good, we already know the main characters, but this DLC tells us that there is more to them than what we thought. Leliana isn't just some crazy girl obsessed with visions. She is something more and has a different side which we never see in Origins.
And lastly the music is great. I played the final section over ten times just to enjoy the music in the last scene.
Get it. It's worth the 7 bucks. And you owe it to Leliana. :D