Unless you never exit the app (i.e. just lock the screen) or you're using it with Backgrounder, there's no reason for it to drain your battery. It stops running when you hit the home button, so it can't take up battery.
I can get 2+ days out of my iPhone battery when it is "standard" firmware, typical usage. When I jailbroke and ran Beejive with Backgrounder (no other jailbreak apps at all) my battery would last less than a day, same usage.