There is not a single theme in the world that would get me to buy a game before playing it. Not one. I won't even buy JJP#3 (Hi Pat!) before playing it, and I am VERY (VERY!) excited for that game to come out.
Every game is so different. There are themes that I thought would be right up my alley that I hated. There were games that I thought would be crap themes that are just a blast to play. Now that games are this expensive, no other course makes sense to me. Wait and see what they do, then decide.