Perfect Dark Zero came very close to being a good game, but ended up stumbling.
The story in Perfect Dark Zero starts out good, but takes a turn very quickly. The first level, in which your character, Joanna Dark, is inserted within a simulation, is interesting enough, once you get past the tutorial bit. The second level, however, you begin to see what's beneath the paint. Perfect Dark Zero demands you to be stealthy, but non-player characters either are totally oblivious to you even as you crouch right beside them, or they immediately spot you, even when you're in the deep shadows. Anyway, the story is that Joanna Dark and her father are being paid to save this guy named Keigler from being ransomed off to a huge megacorporation. After several missions, Jo's father is captured, and you typically have to rescue him, ending in a horrible cliched death. It follows a basic action-movie plot-line, taking twists that leave you wondering, "Why the heck did they do that?"
The multiplayer of the game is slightly better than the story. You can play on an off Xbox Live, and in two different major game modes: Deathmatch and Dark Ops. Deathmatch is the basic, uh, deathmatch, team deathmatch, abd capture the flag. Dark Ops is much like Counter-Strike; you are given money to buy weapons, and then you must go about sabotaging the enemy base, you eliminating all other players, or completely obliterating the other team, or playing a Halo 2's zombies-like Infection. There are a good deal of weapons to use, varying from weak pistols to heavy machine guns. But there is a major problem with the multiplayer, especially when offline: the damage system sucks. There is no other way to put it. Headshots, which the autoaim just make harder, are extremely damaging, as you'll find out as the bots rack up the kills against you (if you're playing on a higher difficulty of bot). Any body shot, however, does pretty much no damage; you'll find yourself reloading assault rifles multiple times per enemy. Even the grenades have a bare effect.
One of the major problems I noticed was that the controls lacked a sort of slickness. There is an autoaim, but it still seems like it is harder to target an enemy, or simply aim. This is odd; even changing the sensitivity, or turning the autoaim off, doesn't seem to fix it.
In conclusion, Perfect Dark Zero attempted to be a killerapp, and failed. It has many, many problems, and ended up being one of the worse first-person shooters to have such critical acclaim in recent games.