Edition: Voyager, 1997
Review number: 117
Polgara the Sorceress is the second prequel to the Belgariad and Malloreon series. The different author attribution of this and Belgarath the Sorcerer apparently reflects not a change in how David Eddings' books are written, but is more an overdue acknowledgement. The story of the world of Belgarath and his family now occupies twelve books, though the two prequels match in length any two of the others.
The first prequel tells a first person narrative of the life of Belgarath, 'the Eternal Man'; this second one is the same, courtesy of his daughter, Polgara. There is naturally some overlap (as Belgarath has been alive through the whole of his daughter's life), but they concentrate on different aspects of the history of the Eddings' world.
Even though they come first chronologically, the prequels would not be a very interesting read before the remainder of the series. The place to start is with the first volume of the Belgariad, Pawn of Prophecy (which was published first). If you enjoy that series and the Malloreon, then come back to the two prequels. (Their scene-setting introductions follow on after the end of the main series.)
Myself, I would be pleased to see the Eddings abandon the arch tone that they take in the whole series, and which is particularly annoying in the prequels. There is a distinct sentimental vein to David Eddings - I once read an interview in which he referred to J.R.R. Tolkien rather nauseatingly as "Papa" - but he is able to jettison it when he desires to do so. His contemporary novels, High Hunt and The Losers, are much better written because in them he assumes a rather different style which works well. To sum up, Polgara the Sorceress is probably for fans only.