Most of the book is just lists of equipment and magic properties, so the majority of it is still useful in 3.5. There are surely some items that need to be changed (e.g. anything that references haste); those will usually be apparent as soon as you read them.
I wouldn't make the A&EG a high priority buy, again because it's mostly just lists. But if you don't need any of the brand-new books, and you can find it on sale someplace, IMO it's worth having on the shelf.