All of those publications, awards and the like, are always very focused on the eastern states. But, have a look at what some food critics have said - I recall the big guy from Masterchef saying a year or two back that despite its size, the cuisine in Adelaide is the best in the country. And he eats a fair bit of food, so I imagine he'd know...
And as to the multi-cultural aspect - Adelaide has had large Italian, Greek and German populations for quite a while, and our Asian food is as good as you'll get anywhere. In fact, I believe that we have the only chef in Australia that is permitted to serve fugu (pufferfish), working at Kenji on Hutt Street (awesome, awesome Japanese restaurant).
People bag this city, but if you have someone who knows the good spots, it's really a great place to hang out and eat amazing food, drink good wine and have fun with friends. If you want to go to raves and clubs, then yeah, it's probably not your thing. Our casino is pretty rubbish too, unfortunately, but c'est la vie :P