The Bhagavad Gita has been translated into English numerous times. I have read and reviewed for Amazon the following six versions in English:
Bolle, Kees W. Bhagavadgita, The: A New Translation (1979)
Easwaran, Eknath. Bhagavad Gita, The (1985; 2000)
Edgerton, Franklin. The Bhagavad Gita (1944)
Miller, Barbara Stoler. Bhagavad Gita, The: Krishna's Counsel in Time of War (1986; 1991)
Mitchell, Stephen. Bhagavad Gita: A New Translation (2000)
Nikhilananda, Swami. Bhagavad Gita, The: Translated from the Sanskrit, with Notes, Comments, and Introduction by Swami Nikhilananda (1944; 6th printing 1979)
(I have yet to read the famous translation by Sir Edwin Arnold.)
The question might be, why bring out another? In the case of the people at YogaVidya, who published this translation by Lars Martin Fosse, the answer is apparent: they want to bring to the English speaking world great works of the yogic tradition. To this end they have previously published Brian Dana Akers' translation of Svatmarama's Hatha Yoga Pradipika (2002), James Mallinson's translation of The Gheranda Samhita (2004), and his translation of The Shiva Samhita (2007). (See my reviews at Amazon.)
The question for the reader might be which book should I buy? The answer depends on several factors. For the devout Hindu and yogi, a translation that stays as close to the original Sanskrit is no doubt to be preferred. Yet even between Hindu and yogi there can be a difference of opinion. The Hindu, especially if he or she is of a conservative bent, may prefer a translation that chooses English words that support a literal interpretation of this great spiritual work, while a yogi, especially if he or she is follower of Patanjali, might prefer a translation that emphasizes practice and study. A general reader might prefer a translation that makes the text readily accessible without having to delve too deeply into Vedic philosophy. A student of literature might prefer the most elegant and poetic translation. And so it goes. A poetic translation must of necessity sacrifice some literal meaning, while a strictly literal translation may make for difficult reading. There is a dictum to which I subscribe to the effect that when translating literature and in particular poetry, something is always lost in translation. Consequently, by this rule, if by no other, no single translation of the Gita will serve. Therefore we have many translations, and as English grows and our attitudes toward the world change, ever so subtly, there will arise a need for new translations.
I think that Fosse's book is distinguished by his clear and informative introduction to the Gita for the general reader. He does a good job of placing the work in the Hindu tradition and gives some idea of its history in English. There is a glossary of names (since Fosse uses the many epithets from the original in his translation) and an index. As with the other books from YogaVidya, the original Sanskrit is given along with the English translation, verse by verse.
What I don't think that Fosse does well is introduce the Gita in a spiritual and symbolic sense. The most important thing that the first time reader of the Gita should realize in my opinion is that it is a work to be taken symbolically. If you take it literally as the story of the personal god Krishna urging the reluctant warrior Arjuna to fight his enemies, you lose the essence of this great work. Better is to understand that the battle that Arjuna faces is not one of swords and arrows, but one of time, chance and circumstance. The central question that Arjuna asks is how to live and why. Krishna essentially tells him you have no choice; that it is a signal of failure and humiliation to give up. And then Krishna gives Arjuna four approaches to life and deliverance (i.e., samadhi): bhakti yoga, the path of love and devotion; karma yoga, the path of selfless work (mainly this); jnana yoga, the path of knowledge; and raja/hatha yoga, the path of discipline or force. It is said in the yogic tradition that when all else fails, the path of force will work if it is practiced with sincerity and regularity. For those of great faith, bhakti yoga leads easily to moksha.
Any translation that is not a work of art by a great poet at the height of his powers (we have no such translation as yet) will, to some extent, be untrue to this great work of spirituality. Just as Shakespeare can never be fully appreciated in translation, so it is with any poetic work. Fosse shows he understands this very well when he writes (p. xxiv) "...a translation is always an interpretation, but an interpretation is not always a translation. The only way to get a truly intimate understanding of a Sanskrit text is to learn Sanskrit." I think his sentiment also hints at why he chose not to write an interpretative introduction.
I have addressed specific problems and choices in translating the Gita in my other reviews, so I will skip them here. Bottom line: this is a fine addition to the list of excellent English translations of the Gita, handsomely presented as usual by YogaVidya, and a good choice for first time readers and for those who know Sanskrit.