I have only been once...and I seriously doubt I will ever go back. Not because the Ghost Bar isn't a great scene...but simply because I never stay at the Palms and unless you make a special trip off the strip to party or drink, then you may not find yourself going to Ghost Bar (besides, I like Voodoo at the Rio much better).
This place, in my mind, was made famous by Real World, and now that no one can remember that particular season, the allure of Ghost Bar has gone with it. Surprisingly for a bar/club/lounge, the drinks are not very expensive.
I did, however, go on a Tuesday evening when the crowd was dead. perhaps being there when it is livelier will change my mind about this place...but then again, when will I ever make a special trip off the Strip to party when there are so many great options on the Strip?