Worth buying, but very hard
You play Joanna Dark. You go by Jo. You look a whole lot better in this game than the last one. You have orange hair in this one. There are a bunch of futuristic guns, and they have realistic sounds. They are better than the guns bungie made up for the halo series. I found those guns pretty lame.
This game is great, but, it is ridiculously hard even on the easiest difficulty. Well, it's not hard on the easiest difficulty...it's just that the aiming is so hard. Good thing on the Agent difficulty you barely get hurt so you have a lot of time to line up the crosshair with the enemy.
The graphics are okay compared to today. The AI is decent, but the enemies look pretty lame up close like gamespot's review said. You only see 2 different kinds of enemies for a lot of the game
Overall, Perfect Dark Zero is a great game, and worth a buy, but you are warned about the aiming. The online play is pretty good, but you have to be good with the aiming.