Recently returned from Syd on AC34 in March in J. My overall experience was excellent. Service was outstanding, aircraft was clean and no IFE or seat issues: this was a big change from my flight down to Syd a week earlier. I wish I had got the FIN number of the AC34 77L because I think it was brand new. I didn't see one mechanical issue, albeit there was a little squeak in the overhead every time we hit chop, but the crew apologized for that. The in-charge went around J and shook everyone’s hand when we boarded and when we were about to land and I was always addressed by may last name
Alas the cheese tray appears as well...however, no baked cookies or Hagen Daz ice cream.
It was also nice to see AC rotate the movies on the return trip. Perhaps that was just my luck, but about 1/2 the movies were different on the way home.

As i remembered from last year, the ANZ lounge in Syd was really nice. Polite staff and food and drinks were better than MLL (smoke salmon, bandwidths, pastries, etc)
(And was a nice treat as I was exposed to RCC service later in the day at ORD )
I thought the window 11A/K and 6A/K are the best seats in J. You get a little bit more storage and very quite seats with the wall. 11 is a bit more quite than 6 because you are furthest from the Galley. However, in 11A/K you don’t get a window, however there is not much to see at night over the pacific, or flying into YVR in the rain. 6A/K had a slightly better window view.
Transfer in YVR sucks, I had a 2 hr window and barely made my flight. I waited 55 min for my luggage to appear on belt 4 in the US transfer area. I really don’t understand why it takes anything over 30 min to deliver luggage, especially bags with *G priority tags.
Anyhow, that’s my two cents, the new XM is very nice. I can’t image much better in the market for a J seat.