You redeem your code in the transactions management section of your "Account Management". Once you've done that, it pops up for you. Like redeeming a card on XBL.
Aside from getting setup which took alittle longer than id wanted from a simple beta,the online feels smooth and natural with little lag issues. the only issues ive had so far is that the maps are waaaay too big. When ur playing team deathmatch it turns into a "lets find the sniper" match, which very much pisses me off among other quirks. The attribute level up system is great too, but I couldnt see myself actually paying for this game seperatly boxed tho.
^^^If you played the first MGO, you would know that the online doesn't even remotely come close to giving a good representation of the single player game.
MGO is more for those who are interested in it, but by no means should you base your decision on getting MGS4 if you hate MGO.
I like MGO btw...A lot better than the first one, and once you get used to the controls, the game is very enjoyable. Maybe because I kick so much ***....either way, I enjoy it. Only complaint is the cover system is absolutely useless online. Offline I could see the purpouse of it...but it is too slow for the online play.