I've been to QBA twice - once when there was college-friends' get-together and second-time when my fiancee gave me a surprise birthday party! Both the times I loooooved the place, especially for its ambience.
The place rocks when it comes to internal deco, though the service is a l'il slow. You keep waving/calling the waiters but they just don't show up. The food is quite alright, though I found some items over-rated.
The best parts about QBA, though, are:
1. Its location in the inner circle of CP
2. Choice of outdoor seating
3. The mocktails