It's kind of up to you really. I've read that a lot of people love it, but I can't get over how slow the enemies move with a couple of exceptions. I don't own it no, but I did play during the free weekend a couple weeks ago and managed to get the xmas achievement during it.
If you like Left 4 Dead, you probably will like KF, but just remember that the enemies are slower-paced and come in waves as opposed to a frantic run through a zombie apocalypse in a shopping mall.