1) Store of value. Much easier to store gold/USD/Bitcoins than the food you will need in the future.

2) Medium of Exchange. Can be used to exchange for real goods, thus avoiding the headache of barter.

3) Unit of Account. e.g. is easily divisible.

Bitcoins aren't great at #2, but gold is terrible at #3. If bitcoins prove to be a lasting store of value, then it will almost certainly be more "money" like than gold.