This short work of 46 verses, whose title means "Wisdom of the Seer and the Seen" talks about the Self as Consciousness (pragyanam-brahma) and perceiver/witness of everything. That the translation has been done by Swami Nikhilananda, who is well known for his translation of many wonderful books (my favorites: Self-knowledge and Bhagavad Gita) adds credit to this book. Even Shri. Subrahmanya Iyer says in the introduction:
The Swami's great literary merits are already so well and so widely known that this work of his needs little introduction from laymen like me. It is a time-honoured belief, a belief as old as the oldest Upanishads, that Vedantic Truth is best taught by those that live it, not by those that merely talk about it. Bhagavan Sri Ramakrsna Paramahamsa, the 'Real Mahatman' of the late Prof. Max Muller, was one such rare and great teacher. And the Vedantic works that are published by the reverend Order of Sannyasins founded by such a Guru have so great a spiritual charm that they make these works most welcome to all earnst seekers after Truth.
Here are a couple of verses:
Verse 1: The form is perceived and the eye is the perceiver. It (eye) is perceived and the mind is the perceiver. The mind with its modifications is perceived and the Witness (the Self) is verily the perceiver. But It (the Witness) is not perceived (by any other).
Verse 2: The forms (objects of perception) appear as various on account of such distintions as blue, yellow, gross, subtle, short, long, etc. The eye, on the other hand, sees them, itself remaining one and the same.
Verse 3: Such characteristics of the eye as blindness, sharpness or dullness, the mind is able to cognize because it is a unity. This also applies to (whatever is perceived through) the ear, skin, etc.
Verse 4: Consciousness illuminates (such other mental states as) desire, determination and doubt, belief and non-belief and non-belief, constancy and its opposite, modesty, understanding, fear and others, because it (Consciousness) is a unity.
Verse 5. This Consciousness [eternal Witness of all changes] does not rise [meaning birth] nor set [death]. It does not increase; neither does it suffer decay. Being self-luminous, it illuminates everything else without any other aid.
In veses 13-15, the book talks about the two powers of Maya: avarna (one that viels/conceals Brahman) and vikshepa (one that projects something else as Brahman). The next verses describe the differences between Nirguna and Saguna Brahman and the modes of attaining each of these.
Note on Saguna Vs. Nirguna Brahman: It is perceived by many that the Upanishads are ambivalent about Saguna vs. Nirguna Brahman. They have case because MahaNarayana Upanishad seems to declare Brahman as Naarayana, Svesavatara Upanishad declares Rudra as Brahman and Ganesha Atharva Sirsha Upanishad declares Brahman as Ganapathi. On the other hand, Mandukya Upanishad and verses from BrihadAranyaka and Chandogya seem to declare Brahman as Nirguna. The learned Swami points out in his introduction to Upanishads that many Upanishads are very clear about which Brahman they are talking about by the use of pronoun "He" for Saguna Brahman and "It" for Nirguna Brahman.
A recommendation: I found that reading Ramana Maharshi's commentary on Drg-Drsya-Viveka helped in understanding it. His commentary is in the book "The Collected works of Ramana Maharshi" and also available online from the Ramana-Maharshi.org website under downloads.
[The original post at advaitin mailing-list also links a classic Advaita text: Yoga Vasistha. I am yet to read it.]
Read the ancient text (including the commentary by Swami Nikhilananda and Ramana Maharshi) and contemplate on the nature of the Self!
Postscript: The following link is also relevant.