Real vampires don't sparkle.
First of all, Festival of Blood is not a DLC (downloadable content), or game add on. It is a stand alone game, the requires neither inFamous or inFamous 2 to play, you can find it in Playstation Store for $9.99. Which I think is a pretty sweet deal, the game is about 2-4 hours long. But that's just story wise, there are other things to enjoy besides the story and UGC (user generated content).
I'm not going to explain the entire story, because that would just ruin it, and take way to much time. So long story short, Cole McGrath gets bitten by a vampire on Pyre Night; a big celebration that goes on in New Marais. But Cole wasn't bitten by just any vampire, this was the work of Bloody Mary. And unless Cole would like to become a vampire for all eternity, and feast upon his fellow humans, he must find Father Ignacius's barbed cross, and stake the monster responsible before the sun rises. Easy right?
Festival of Blood's comic book style scenes are fantastic, and the animated ones are hilarious. Overall it's a fantastic addition to the inFamous storyline.
Also, like in the previous games; there are plenty of collectibles to pick up for trophies. In FoB, there are Mary's Teachings, that will when found will upgrade your blood meter and powers, as well as finding Canopic Jars.
If I haven't already said it, the game is just plain fun. So what are you waiting for? Go! Go play it and see for yourself!
I hope you found this review helpful, don't forget the thumps up! ;)
~VGN