What is unique about the Annex in the book The Giver?

In many ways, the Annex is the embodiment of what was before the time of Sameness.

It offers privacy to the Receiver of Memory is several ways:  it has a lock, a buzzer on the door, and there is an on/off switch on the speaker. 

It also has information.  Unlike the highly restricted reading elsewhere in the community, there are books, books and more books in the Annex on tons of subjects. 

The furnishings in the Annex are more comfortable and luxurious.

Of course, what happens in the Annex is unique, as the Giver passes on memories of all that has been removed to the new Receiver of Memory, in this case Jonas.  Accordingly, the Annex has joy, pain, color and many other experiences.