Currently sat in the SIN QR Premium lounge and I can't say anything bad about it. We visited QF F briefly for something to eat (it's hard to turn down their Salt and Pepper Squid and Laksa), but it's practically a zoo by comparison to the QR lounge which is an oasis of calm.

I count at present 8 passengers total and easily that many staff members making sure everything is taken care of, but not in an overbearing way at all. I feel a little bad for some of the staff who are standing around not doing anything, though!

Would definitely recommend if you are on a Oneworld J/F ticket.