We too have flown Delta internationally on the SYD/LAX route and domestic within the US and I have to say we also had no complaints, so much so that the 5 of us are flying them again next month.
Every flight we had was on time, the only unpleasant part of the trip was the awful immigration and customs hall on arrival at T5 at LAX. It all seemed a bit "temporary", the air conditioning was non existent, and the whole thing was very cramped with a low ceiling - reminded me of an old school assembly hall rather than a major international airport. And there are absolutely no shops or toilets - my DS who was 6 at the time waited to go to the bathroom until we got off the plane as I expected there would be toilets at touchdown but there were none! But bless him - he hung on and on right up until we got through customs and out into the main lobby. Having said that though, there were wooden ramps and some scaffold up, so I feel that either they were renovating, or we were diverted to something temporary for some reason. It might be different this time. It's just not as glamorous or as spacious as arriving in Sydney, not by a long shot.
The AVOD on the aircraft really are great.
I found the seats fine - I have pictures of me sitting in them and like Shutter, I'm not exactly Kate Moss, and I had plenty of space.
But as the author of this article he points out - that fare he got at $900-odd including tax - that is CHEAP. If he doesn't think the airline or the service was up to scratch, pay more and get more. Delta doesn't profess to be a luxury airline, but it's not a budget airline either. It's nowhere near the Emirates and SwissAir league - but it's not Jetstar either.