The world was perfect before the fall. When Adam and Eve sinned, they cursed every living thing with death. However, with the downfall of sin also came the power of free will (aka the power to make choices; "the knowledge of good and evil").
It's still not very nice that he's killed millions of humans in forms of floods, plagues, and the well rounded smite.
However, it's probably one of those instances where the Bible shouldn't be taken literally, as if you do that, it starts to counteract the morals it tries to pass off.
It's a great storybook and teacher, but yeah if you take God as literally as the words in the Bible tell him to be, I can at least say he wouldn't be very fun at parties.