The main problem with the game lies in the annoyance of "will they or won't they switch?", which gets old fast for players used to normal PvP card games where once you put a card in, it stays in until it dies. Also, Game Stop doesn't have anything to gain by promoting it, as there is no easy money to be made.
using feast of blood, you should gain at least one HP even if your opponent has only one HP left. blood-drainers are weak enough as it is -- rounding down on odd numbers of HP during drains only exacerbates the problem. HRRUMPH!