...you need to redeem the code (through XBL at least) and start a new game before you will see these new items which consist of: shotgun, sniper rifle, 10k credits.  I redeemed the code after a couple of hours of play and went to JC Denton's apartment (woops Adam Jenson) and the items weren't there. I'm in the second city and still no items.  So I suspect you must start a new game for the items to appear. 
 
If you're like me and forgot to redeem the code, don't worry about it.  Just save it for your next playthrough.  Inventory management can be a pain in the ass so if you're worried about keeping 2 "unique" items through your first playthrough it may lessen your fun factor. 
 
-end PSA- 

Hey thanks for the heads-up!

This is a stupid question and I'm not far in, but do you have a secondary inventory/locker where you can stash stuff? I was collecting a bunch of guns and I ran out of room, and I'd just like some place to put some extra stuff that I don't always want to carry.

@Napalm: I'm getting to that point and am probably just gonna start dumping items in the apartment.

@Napalm: I'm getting to that point and am probably just gonna start dumping items in the apartment.

@Napalm: There was an implied "no" in my response.

Thanks for the info! I'm a good bit in and forgot about the code in my excitement to start up the game. I also thought about dropping the items in the apartment when the thought occurred that they might disappear when I left. So it's safe to assume that doesn't happen?

@Napalm said:

@subtek said:

@Napalm: I'm getting to that point and am probably just gonna start dumping items in the apartment.

I asked a question. Is there a locker/extra storage in Adam's apartment?

There's really no reason to keep anything you aren't using. Sell it off.