It's had a fair share of problems lately, but it's still a great game.
There are several game modes, most of which are taken from the original Korean version of the game. These include Deathmatch, Team Deathmatch and a Capture the Flag style game aswell as a team vs CPU game that has some decent rewards, although most of the games fun comes from the Player VS Player interaction.
The Clan system is pretty simple, having your own Clan can be easy and upkeep isn't hard. There is no clan page or anything, but rather a Clan tab in which all info can be easily accessed. This allows clan wars to be easily set up, although there could be some huge improvements, but it still works.
The graphics are pretty poor, and even then there is still a bit of lag from slower computers, which can cause players to think you are cheating, and even get kicked from games, so playing it on low quality is reccomended. The music in Gunz is very limited but it's fast paced and sets the mood well. There is also a very wide variety of items and armours to allow you to customize your character. There are grenades, swords, duel sword, machine guns, hand guns, cloaks, rocket launchers and a wide variety of other weapons to choose from.
Overall, Gunz is a great game if you are lucky enough to avoid alot of the errors the game has been having lately and can actually play.