Product-Reviews writes: We wanted to play the good part in Dawnguard, which meant hunting vampires, but at the same time being on the opposite side of Serena didn’t sound like fun considering how nice she looked and sounded. You can of course create another save file and play Dawnguard a different way in the future, which is recommended for getting the most out of the DLC. The choice to join the vampires or Dawnguard had been made before the Skyrim DLC released, for a number of players, but we wonder how many gamers had their minds changed after helping Serena escape?
80°
30°
40°
20°
Ad 
450°
0°
20°
30°
30°
30°
It doesn't matter which side you choose, it's still exactly the same terrible story.
You go to the same places, do the same things and the ending is the same no matter who you pick.
I wish you could turn her human at the end and marry her
I like her interaction with where you go in the game.