The Hong Kong Plaza Premium lounge beside gate 1 (previously known as the 'east' lounge) is a decent, if not exceptional, pay-in lounge.
The lounge is all underground, without windows, and this can lead to a somewhat claustrophobic feeling with at much furniture as possible crammed into two not overly large rooms.
However, the lounge is well-furnished with comfortable seating, shower rooms, a dining area, buffet catering, noodle bar and with wine and beer on draft.
There is free Wi-Fi and if you can get a booth to yourself at the back, is an acceptable lounge for a few hours.