The fourth edition claims to have these advantages: it includes (1) a selection from Rousseau (2) additional material from Locke's Essay and (3) a new translation of the Meditations.
(2) consists of a short chapter on faith and reason. In exchange, we've lost II.11, on abstraction. Since there's little material from Book III, and nothing from III.vi, it's very hard for the reader to make sense of Berkeley's extended attack on abstract ideas in the introduction to the Principles.
Re. (3): Inexplicably, the editor has decided to replace John Cottingham's standard 1986 translation of the Meditations with a 'new' translation by Laurence Lafleur, first published in 1951. Perhaps the editor had no choice, but it seems disingenuous to present this as an improvement.
Moreover, the third edition included a crucial selection from Kant's first Critique (the transcendental deduction); this has been deleted.
This is a big step down from the third edition.
This anthology would (does?) make a good text for a history of philosophy class as well as a companion to classically-inclined philosophers such as Nietzsche (who Kaufmann has played no small role in creating for the English-speaking world) and Heidegger. It is as good as an anthology as I've seen covering the pre-medieval period. That said, the volume suffers from a lack of depth and would benefit from the more extensive footnotes and references to primary sources or translations that I've grown accustomed to in Kaufmann's other works.