I don't mind a video game being short, I'm more concern about Replayability and it's cool to see that Capcom is adding more game modes giving us more variety. When we look at RE5, after you went through and beat the game with all the weapons and other unlockables you have nothing but Mercs to fall back on, and eventually that was boring and frustrating after a few rounds (Even with friends) then Versus is lame, but with RE6 we have Ada's scenario, Mercs, Agent Hunt, and 3 Main scenarios.
So this game may last me until something else that catches my attention is released or announced.