We haven't been eating out nearly as often as we did in Sydney, but so far our experiences in Oxford have been quite good. (A comparison to Sydney, with thirty times the population, may not seem fair, but the comparison is with that part of Sydney I know - areas of the Inner West, CBD, and Lower North Shore - which is not so different in size.)
There's great diversity. Compared to Sydney, Oxford has more North African and Caribbean food, more Bangladeshi/North Indian/Pakistani food, and more Polish food. There is less Chinese and Thai and Japanese and Italian and South Indian, and hardly any Vietnamese or Indonesian.
Quality is not just a matter of price. When we moved to Glebe (in Sydney) we sampled eating places along Glebe Point Rd pretty much at random, with better and worse results but not one really terrible experience. Here we've had satay chicken that had the consistency of rubber, and before I joined her Camilla encountered "fish and chips" that she couldn't actually eat.
At current nominal exchange rates, prices are on a par with those in Sydney. In addition to the 40%+ fall in the pound since I was here in 1997, the UK appears to have experienced lower inflation than Australia. In purchasing parity terms, however, eating out remains expensive.
A few favourites so far:
The Magdalen Arms, one of our local pubs, has a good quality restaurant, serving general Modern European food. At around £10-£12 for mains it's quite reasonably priced - much better food than our local pub in Glebe, the Nag's Head, for around the same price.
Jaipur is a new Indian restaurant on Cowley Rd, which we've eaten at several times. It also does take away.
Thai Orchid (on St Clements) is the best of the Thai places we've tried so far.
The Magic Cafe, just around the corner from us, isn't going to win any culinary awards, but has cheap hearty vegetarian meals and is bright and cheerful. For a more traditional cafe, I like Cafe Coco, which does a nice full breakfast and has a decent cup of coffee.
For lunchtimes in the city centre, there's a plethora of good sandwich shops and so forth. I recommend Harvey's, the Gourmet Burger Kitchen, and Fire & Stone.
One of the things we miss is the excellent Sydney yum cha. We've tried a few places here - Liaisons and Lan Kwai Fong - and they are ok but really not in the same league.
I only really know Jericho/central Oxford and the Cowley Rd area, not having explored the eating options in Summertown, the station area, or Headington at all.