Like most Aussies I love our flag but I have a niggle deep down inside me about the union jack's prominence. I understand and respect many of our relatives (including mine) fought and died under this flag but a flag is an official symbol of a nation designed for the time. And times change, and people change, and societies evolve. And ours has evolved a lot since 1901.
As a kid I sang our national anthem "God Save The Queen" every Monday morning at school. I'm glad that's not our national anthem any more and I reckon most Australians would be. So I'm not averse to changing the flag at all.
The flag in the OP seems pretty good for the symbolism it contains and I liked it more after I read the link. Not sure about the green and gold stars though, think white stars on blue like current design looks better.
Used to think this one was a good one
http://www.flagoz.com/ but like the OP version better after comparing them.
Anyway, this will be an interesting thread and no opinion will be more valid than another. Will be a difficult process to change the current flag but I believe it is inevitable in time.