It's free to play but they've stated that you'll have the ability to purchase the game and get all champions, including future ones (that last part might not be set in stone).
Had an amazing time! BF3 tourney was seriously intense. We got second, losing by only 3 kills. Congrats to the guys on Delta squad for beating us (Charlie squad) in the finals!!
Had a great time at the event; can't wait to go again next year. It's really a shame the machines running the bf3 tourneys were having so much trouble though.