It killed mine apparently... I've seen a huge increase in battery life since turning off everything but Find My iPhone and Backup. I assume it's because I had a GMail account syncing with Exchange as well so it was polling twice as much as just having the Exchange account, which doesn't bode well for battery life.
It's probably important to add that I am a very light user. No games, no music, no videos - just a few calls (yes, I actually use it as a phone!), a little surfing, checking emails, occasional use of Reminders locator function.
My guess is your experience is probably more common than mine.