You get to use the crap BA "F" lounge at JFK which is really a fake shared lounge with cheap facilities (as the actual BA F pax use the "Concorde" lounge and you cannot).
You'll get to remain sat in a bleak little sterile area in YVR with some bottled water in a box for your pleasure, along with all else on the plane, for about 60 minutes (or you may get lucky like me in December and get stuck for 2 hrs 30 minutes there).
Then - the best part of all - you'll get to TRY to sleep on the YVR-JFK leg at all hours of the morning with the YVR-based crew chatting to each other in the galley up front the entire 5 hours, plus several of their breathren coming up from the back to chat with them as well. This is THE reason I try to avoid that routing whenever possible.
In December the soup was "lobster bisque" for BOTH the HKG-YVR and YVR-JFK leg, and they served smoked salmon as the starter on BOTH of these legs (also caviar ex-HKG) which was just a tad redundant (and who came up with that moronic concept?)! The food on the second leg is never really very good.
But enjoy!