It launches in two hours mate.
No idea if there will be a demo, now that I think about it, that is really something they should do.. let people play one map so they can try out the game.

In before 'but the game doesn't have that many maps and you could play one map forever' : bf1942 had a demo with 2 maps and people did indeed play that demo for years. If the game is good almost all players will be craving for more.