First of all please forgive any typos and delirium as I've been awake 25 hours.
Flew United Premium Plus SYD-LAX yesterday, then transfers at LAX and DEN (where I now am).
SYD-LAX in United's premium economy was surprisingly pleasant. Crew was friendly and catering a marked step up from what I'd expect in economy. It felt perfectly between that and business. Bar service before the meal, and was given two mini-bottles without asking. Wine with lunch all of 10 minutes after, and then another coffee/bar service after, at which point I was given two mini-bottles of Baileys. Two of the four mini-bottles found their way into my hand luggage as I couldn't keep up. Daytime flight so couldn't sleep, despite the libations.
We arrived LAX early; too early. Apparently LAX doesn't open customs/immigration until 6am so we had to wait about 15 minutes. It took less than 30 minutes from de-planing to passing immigration/customs and re-clearing security for my domestic flight.
I can't report on extra baggage allowance unfortunately (which is a particular issue it seems with the new UA partnership), but my Virgin Gold status did give me Premier access and Zone 1 for all flights. I was ready for a discussion and/or having to pull out my Star Gold card but no issues whatsoever scanning my boarding pass for lounge access on domestic sectors at both LAX and DEN, which is noteworthy as UA's own website seems to suggest they only give access before the international flight, which is obviously not the case.
United Clubs at LAX and DEN perfectly fine. Not as extensive food and beverage offering as the AMEX Centurion on both locations, but far, far less crowded and noisy.
In short, far smoother than I feared/fretted. And once the SCs post, I'll be VA Platinum.
I need a nap.