I found that fun for a while, but there really isn't a challenge if you know what you are doing, and there is alot of hackers who use wallhack seeing through walls) so it get's really annoying after a while of constantly being killed by those people.
My favorite mode was always the ghost mode (I think that is what it was) but that was full of wallhackers and people who had hacks to see the ghosts fully. One thing I really never liked was the fact that you get so much money after the game, but then you use almost all your money except for $2 of it to repair your gun, and I have tried just ignoring the gun and that is NOT the way to go. If you play just an hour of the game, you will quickly learn how much of a difference a perfect gun is from a slightly damaged gun. The gun will have less accuracy and less power so repairing your gun is really a must.
But then there is ghost mode, when you play as a ghost you can only use mele weapons and those don't take damage so you could keep all the money you make from it, which was one of the main reasons why I used to always play that mode. But even in the ghost mode, you barely get any money, any real way to buy guns since tey are so expensive is just to level up and use the prize money to buy a new gun.