Have just returned from something of a BA Odyssey, traveling...
I flew BA Y+ SYD-LHR & LHR-SYD last month (among other EU flights) and it was a bit of a let down. I scored a bargain when BA was promoting switching the aircraft from 744 to 77W. Ticket was only $2000, which is less than I paid in 2012 for Y to LHR.
The aircraft was G-STBF, the newest 77W in BA's fleet, but it had issues in SYD so we were left sitting at the gate for an hour while the plane was "re-booted" as the captain described. The cabin was clean (unusual for BA) but as with Y on the 77W I found the seat very hard. I'd chosen 21D which is a bulkhead seat, so there would be nobody reclining into me and there would be a leg rest.
Leg room is fine - I'm 6'1" and could stretch out my legs to rest on the bulkhead. But the leg rest is useless, it doesn't come out far enough so your feet end up on the ground anyway. Most annoying about this seat is the curtain between J and Y+. When the FA's stomp through the cabin they toss aside the curtain into whoever is sitting in 21D, meaning I was woken many times on the SIN-LHR leg.
Food SYD-SIN was the best of the flights, SIN-LHR & SIN-SYD was the worst by far. LHR-SIN was edible but as this flight was also delayed the food was dried out.
Crew on all flights were cold and surly - BA intra-EU had better crews, even IB intra-EU were better. The above mentioned stomping through the cabin is pretty annoying.
Coming back from LHR the flight was again delayed, this time until midnight. At least BA notified me via text message and email of the delay and advised that check in would close later. I had lounge access courtesy of QF SG status so could fit in a leisurely shower at T5 Galleries South. But I really felt for the pax who didn't have lounge access - T5 shops all close at 10pm so they had a 2 hour wait in an empty terminal.
I chose a better seat for the return flight - 25K by the window. The foot rest is much more useful, and there's a gap between the seat and window where you can leave the blanket/pillow/kit etc when you're not using it.
All in all I wouldn't want to pay more than ~$500 more than the Y price for this Y+ product, but the flights were packed in all cabins so looks like BA may be sticking around on this route longer than I thought.