Pros and Cons:
1. It was easy to fall in love, if you will, with the protagonist daughter, Serana, of the “Clan Volkihar.” (I was enthralled with the fact that Serana remained in the game to be used as a companion. Watching Serana run off toward the dock alone, from the steps of Castle Volkihar, in search of cure for Vampirism was heartwarming. )
2. The sultry voice acting was superb as was the dialogue the actress voiced.
3. Thanks to Bethesda! The cinematography was exceptional in keeping with Skyrim’s amazing artwork.
4. The entire storyline was very well written, I think. (More so than the main storyline of Skyrim, which is rather disinteresting. Given that I played Skyrim for more than 500 hours before I ever finished the main quest and it’s not so fun filled ending—to say, because of all of the negative feedback about it in the forums.)
5. I was impressed with the fact that Dawnguard was designed, in part I believe, as part of the game itself. Wherein, you could jump around doing different unrelated quest after quest in both the game and Dawnguard with ease. (Not like some of those poorly designed DLC's in Dragon Age Origins, which I wasted money on.)
Personal Cons:
1. I am not necessarily a fan of multilayered mazes and there were more than my patience could handle at times. And, with that I fault my elderly mind, along with my frustration of following Skyrim’s compass. (I have never been able to quite grasp the compass and its many way-points.)
This probably seems like a bunch of rambling, but having played Dawnguard I am anxious to see what comes next. It was well worth the $20 bucks.