Reiner Knizia games are known for the subtlety of their play, as well as the simplicty of their mechanics. He may have surpassed himself with 'Vampire,' a game that causes an immediate 'That's it?!?' reaction when you read the rules.
When I get a new game, I usually play it out against myself a few times so that I can find any hidden pitfalls, and then teach it to my friends, who absolutely detest reading through the rules of a game. What I discovered was surprising.
Players who just dive into the game will fail to see the subtlety of it, and will merely go for a quick end to the game, with short runs and hoping to cover all six colors. This is almost always a road to defeat, since those short runs of cards usually mean that the color will not be scored at game end. It is much better to work toward longer runs of cards, even if a color or two is missed.
On the other hand, if two or more players work toward long colors and another player tries for short ones, there is the slight chance that this player can sneak through with a win by picking up those colors missed by the other players.
Like Lost Cities, there is an overwhelming chance that the casual gamer will underestimate this game and give it a bye rather than a buy. If you want a simple game that calls for some tough decisions, stake out 'Vampire.'