The Indian-Pacific's motto is "The adventure that spans Australia". We didn't ride on the Indian-Pacific during this visit. However, having ridden on the sister line, the Ghan, we feel completely competent in recommending the Indian-Pacific to those travelling anywhere across Australia on the Sydney-Adelaide-Perth line.
The Indian-Pacific makes the Sydney-Perth journey twice weekly in both directions. If you have the time and the knack for an adventure, I seriously suggest that you take the Indian-Pacific on at least part of your transcontinental journey. I'd think that the Adelaide-Perth run across the desert of Western Australia would be awe-inspiring.
If you're traveling in first class (Gold Kangaroo) and you make advance booking, you can bring your automobile along on the train's motorail for a reasonable cost...something like A$100.
For all you train lovers, here are a few Indian-Pacific facts, courtesy of "Platform Magazine", published by the Great Southern Railway Company of Australia...
Sydney to Perth, 4352 km (one way), the trip takes 65 hours.
Average length of train, 403 meters, 15 passenger cars + locomotive + motorail
Average speed of the Ghan 85 km/hr/max speed 115 km/hr
Weight of the train is 735 tons.
The emblem of the train is the wedge-tailed eagle. Its massive two meter wingspan symbolizes the epic journey of the Indian-Pacific.
The basic routing of the train, is as follows:
Sydney - Broken Hill - Adelaide - Port Augusta - Cook - Kalgoorlie - Perth

