Lets start with the good. I like the premise and the the music is suitable. I also like that between matches the pattern on the back of the cards changes. Its a very nice little touch. The graphics are simple but intuitive. This is not a game that requires epic levels of visual splendor to tell its story and you did well with the tools you selected.
It was said by others that a tutorial at the start to understand the core mechanics would have been helpful. This is me seconding that notion.
Once I figured out that the best path to success is many little, incremental victories rather than the singly sweeping success it made things more palatable. Personally, I think there should be an achievement for winning a match without winning a round in the match.
. . .
so there is this one little thing that bothers me. I can't help but feel that its not a 'fair play' game. In other words I feel that the game is changing the values of the face down cards after they've been dealt, especially against the higher stakes opponents. Like the game won't determine the value of a given card until it has to (either by flipping it or a hint being used) Given the context, I can accept it; Evil Vampires will be Evil Vampires after all. I also would not object if the placement were not randomized. Again, Evil Vampire's gonna Evil Vampire. The notion, which I could not shake, took the edge of the entertainment and added a little frustration to my play. Personally I would feel better if the game flipped up all the cards once you passed just so you knew.
Bottom line: A solid but simple game with solid but simple mechanics executed fairly well,