While the OZ lounges do have some issues and there's a lot of room for improvement, they're way better than almost all *A lounges in the U.S. and Europe, at least in my opinion. Still though they're a far cry from the old, now closed, SKL at ICN. As to comparing them to the SQ lounges in SIN, I'd say there's not really all that much difference, though hot food service times at the OZ lounges is pretty poor, so if you want to eat the SQ lounges would defintely be a big step up.