Hi Gemma,
Finding a new take on one of Australia’s most photographed buildings is never easy… which is why I like what you have done with this photograph.
Placing the camera on a tripod with a slow shutter speed and then capturing the woman doing step-up exercises off in the right frame helps to show this landscape is more than just a show space. You get the feeling that people really use the space.
At a guess, I would say you used a graduated filter to darken the sky, either at the time of capture or in postproduction. I don’t have a problem with graduated filters but they do need to be used with caution; what you will notice in the photograph is that the top of the Opera House has been darkened along with the sky. Ideally you want to darken the sky without affecting the building.
One simple way of doing this is to make two photographs, one with the graduated filter and one without. I would combine the two photographs in Photoshop and use a layer mask to separate one from the other.
One more suggestion: ease up the cropping on the right-hand side of the frame (if possible) and crop the top and bottom of the picture (as in the example below).
Otherwise good effort!
Cheers,
Anthony
Image Doctor's edited version