2002 Revision
In 2002, a third work was produced. This one, edited by Alison Latham, goes back to the original title and to the single-volume format.
Latham assembled her own team of over 120 contributors, some of whom had contributed to the prior (Arnold) edition, and others drawn from her own previous editing work (for example on the Grove Concise Dictionary of Music). This edition consists of some 7400 articles and aims to bring the work up-to-date, for example, in its coverage of areas such as electronic music and computers.
The 2002 revision is, indeed, more up to date, handier and more affordable than its predecessor. However, the 2002 revision abridges the text and eliminates most of the illustrations and on certain subjects is clearly less useful.
Read more about this topic: The Oxford Companion To Music