Metadata can be added to books. Here I've created a page in the small soft cover book I already had started and dragged a photo on to it:

I need a border to leave room for the metadata. To do that I drag the corners in and then change the way that Aperture fills the box by right-clicking and changing from Scale To Fit Centered to Scale to Fill:

Now adding metadata should be easy. I make sure I am in Edit Layout mode, select an image, click on the Add Metadata button::

And there it is. Or is it? It turns out that this does not work. At all. It turns out that you can't add metadata boxes to small soft cover books -- or at least I can't make it work. So lets start again. I'll pick a new theme, say Special Occasion, and edit it a little. Now let's add metadata to this image:

After moving the new metadata box I get this:

And now I can go to the metadata format drop-down and select something else:

Such as aperture:

But that is not very friendly. It looks like I have to create a separate box for each item I want to add. No metadata sets here? Apparently not. I hope that is coming in a later version. Anyway here is the result:

Another neat thing you can do with books is to automatically flow all the photos into the template and then rearrange:

Some of its choices are inspired, like this one:

And this one:

Unfortunately there is no way to randomize the images into a book. That would be a real boon.

A neat feature of the books is that as long as you are in Edit Mode, if you drag photos about on a page they will swap, not replace. In other words, there is no need to cut and paste and reposition. Drag to rearrange, simple as that.