World Bar offers a real Kings Cross experience and must not be missed. Of course there is downfalls. The entry fee is usually around $20 to get in and just like any club/bar in the cross, drinks aren't cheap. No local fees here. Cues are usually a pest too. I recommend finding a promoter of the club so that you can get into the club via the guest list otherwise you will be looking at waiting till after 1am before checking out this great venue.
Although such a great venue, the dance floors are quite small and when packed it can be very clustered resulting in many drinks being spilled across the dance floor. However the music certainly makes up for it. World class DJ's continue to play which usually attracts great crowds, so again try to get your stamp nice and early.
The night to go would probably be a Saturday night as it is usually the best night but don't expect it to be a cheap night. Overall I would recommend World Bar to everyone wanting to have a bit of fun and cut loose but in saying that, expect a clustered dance and expensive night. Those that dance like hooligans be aware.