The wines will be good but nothing anywhere near as expensive as Bin 707 or Cathay's Chateau Lynch Bages. Most of the wines are around the $AU35-$50 retail mark compared to the Bin 707 which is closer to $100.
The best wine I've had on Qantas recently (in the last 2 or 3 years) was a Henschke Mount Edelstone but that was only on board for the inaugural flight into New York - I think perhaps James Strong preferred a superior wine to Qantas' standard first class offering! Luckily there was one bottle left on the return leg JFK-LAX of that first flight and after the flight attendant recommended it to me (sitting nearest the galley in 1st), I convinced her not to recommend it to anyone else. By the time I got to LAX I was very happy and by the time I got to Sydney I was feeling dreadful. But it was a cross I was more than happy to bear.

Just looking over some of the recent winelists from 1st on QANTAS:

Champagne - sometimes still Krug but more often seems to be Charles Heidsieck Reserve Privee Mis en Cave

Whites - Tower Estate Riesling, Mount Pleasant Lovedale Semillon, Penfolds Adelaide Hills Chardonnay

Reds - Barwang Cabernet Sauvignon, St Huberts Pinot Noir, Woodstock The Stocks Shiraz

Dessert - invariably (it seems to me) Carramar Estate Botrytis Semillon

Port - Para Liqueur Port