Many great scholars have written the commentary on the Vishnusahastranama. Most illustrious being Parasharbhatta and Adi Shankaracharya.

Around 11th or 12th century...Parasharbhatta's father was a prosperous " kultalaivar" in Kanchipuram district.. also a very close devotee of Sri Ramanujan. When Ramanujan left Kanchipuram and went to Shrirangam his disciple also gave up all his land and property and along with his wife went to serve his master. He also renounced all his material pursuits and lived a life of a brahmin..living on bhiksha. In due course, with the blessings of Lord Ranganatha, the couple was blessed with twins. Sri Ramanujan named them Parashara and Vyasa. These kids all most grew up in the temple very near to the lord. So in that sense they were the foster babies of lord Ranganatha and goddess Ranganayaki herself..Parashara grew up to be a great bhakta and scholar both in sanskrit and tamil. Later Sri Ramanujan appointed him the chief pontiff of the vaishnava faith. Such is his greatness that when we say bhattar we mean Parasharbhatta only.. under the command of Sri Ramanujan he wrote the commentary on Vishnusahastranama and called it 'Bhagvadgunadarpana"...mirror of glorious qualities of god.

About the greatness of Vishnusahastranama....why it is so great .. bhattar attributes six qualities to Vishnusahastranama...

First and foremost it is the essence of Mahabharata he says...

Secondly because the rishis have sung it, chanted it again and again...

Then it was compiled by Vedacharya none other than Vedavyasa...

It was expounded by Bheeshma as highest of truth, highest of tatva...

It has been accepted by all the elders as pinnacle of dharma...

Its teachings are in congruence..alignment with the Bhagvad Gita and other scriptures...