Pros:

- plenty of detail put into the map

- guns and ammo were easy to find

- The server I played on had Counter strike guns, so it was even more fun XDD

- Long campaign, which is good. Took me and my mates an hour to finish. (58 mins)

Cons:

- The NPC's seemed kinda stupid on the office maps. They were shooting through walls and shit.

- The ending was really difficult. The option to speed it up was nice though. 

- I think at least 15 minutes of our game play was trying to figure out where to go. 

Conclusion:

I've played this through 3 times and enjoyed it every time. Defiantly worth a download.