I visited this WHS in November 2016. I had already marked it as a top WHS and it surely didn't disappoint. Even though there is another great WHS relatively nearby (Ajanta Caves), I think both deserve a lengthy visit (if not a revisit) for different reasons.
Ellora Caves is made up of 34 caves from 3 different religions and the majority of the caves have beautiful carvings and/or sculptures apart from the architectural genius involved.
The closest cave to the entrance, Cave 16 or Kailasanatha temple, would easily deserve inscription alone for its unique architecture and complexity (picture). Any point of view but especially from above will help you appreciate this mindboggling piece of architecture.
My personal favourite were the Buddhist caves, especially the 2 and 3 storey ones for their rock-cut Buddhas and Cave 10 (quite similar to Ajanta's Cave 26) for its acoustic properties. The Jain caves are also worth visiting but to me were the least interesting having visited other Jain temples in India.
I spent a whole day at Ellora and I kept revisiting Cave 16 for different lighting, angles and perspectives and Cave 10 whenever a Buddhist monk visited to experience the soothing chants echoing throughout the cave. On the way to the caves from Aurangabad, I also stopped to visit the Daulatabad Fort and Minaret.
I would strongly recommend visiting Ellora and Ajanta on different days if possible so as to take them in at leisure.