I first encountered the Tao Te Ching in the Mithcell translation as a sophomore in college, and we read it--fitting the context of a course on world religions--as a religious text. What is really nice about D. C. Lau's translation (and he mentions this in his fine intro) is that, in keeping with a longstanding tradition in Chinese culture, he attempts to restore some of the political import to the text. Re-reading Lao Tzu's lyrical fragments in Lau's rendering of them really brought home to me an aspect of the text that is completely overshadowed, in most translations, by the religious angles that are important but not sole determiners of the Tao's relevance and message. (This view sees me in disagreement with the avowed "Taoist" reviewer below who lamented Lau's attention to Lao Tzu's political import.)
While I heartily disagree with the political message of the Tao Te Ching--which sponsors a hands-off, laissez-faire, small-government formation, letting everything work itself out without intrusion from leaders and other well-intentioned officials, as if things ever just work themselves out on their own!--I appreciate Lau's efforts to recover in his translation a crucial, crucial aspect of Lao Tzu's thought, and one that has been shuffled under the magic carpet by Taoism's New Agey popularity among many Anglophones.
The Tao Te Ching is a great book of early Asian Philosophy. Unfortunately, this is by far the worst translation available, which is regrettable because I love Penguin classics. Penguin is a great publisher of the classics. I would really like to see Penguin publish this timely classic by Stephen Mitchell, which most will now admit is the "best" translation of this great book.
Dr. Lau has a good "introduction" for the book but his "English" and word choice is rather poor and outdated. Comparing translations is good, since I have quite a variety of translations to look at. But for a really good translation, see Stephen Mitchell's version.