Worth the £10/$15, great online, good co-op, it'll keep you occupied for a while.
It has no campaign, which I was quite disappointed about but it offers 4-player co-op called Black Ops, which is just basicly get from point a to point b but is quite challenging at the same time.
The Multiplayer is 16 player and features game modes like Deathmatch, Team Deathmatch, Domination etc, it has a simlar ranking system to Call of Duty, so plays of CoD will be quite familiar with it.
The Customisation is wide and you can build your own personal gun with different perks, you can also choose between 'Tags' which a like little keyrings which you can attach to your gun giving it a small boost in firepower, fire rate or health etc.
It's definitetly worth £10/$15, it plays like a £40/$60 game which is quite the bargin if you are short on cash, a few issues like the matchmaking is quite slow and can take a while to find a game, i've only had this problem a couple of times but it seems a problem with other players.
Overall a very good DLC game, if your wondering if you should buy it, try the trial which offers up to an hour of gameplay online.