Does it matter which way a door is facing in Minecraft?

Depending on which way I'm facing when I place a door, it will either be on one side of a cube border or another. Are there any game mechanics that make use of the door's alignment which I should be aware of, or is it purely cosmetic?

Door placed from this side

Door placed from opposite side

Solution 1:

I believe doors allow attacks in one direction. So if you mount the door from the outside, you can attack through it, but you cannot be attacked (or be shot by skeletons) from outside.

I can't find an official source on this, but this thread discusses it (see the last post), and this blog entry (see number 5) seems to confirm it.

Solution 2:

The direction of the door dictates where it will be (and obstruct) when it is open. In cases where safety is not an issue, just convenience, I place doors such that they open onto the side of the opening that I am less likely to run into.

Solution 3:

I think it affects the direction the door opens. Although I am not sure if the door opens away from you as you place it or towards you.

This can be important if there is a mob on the other side of your door. If it opens towards the mob then you can safely bash them through the door. If it opens towards you then you might accidnetally open the door and let them in!