Rating: 

1) Finding a particular CSS property is more difficult than it should be. Not only should the index be populated with all properties (properties should stand out), but each page should have a letter tab that's easily visible as you thumb through the pages ... so you know if you're nearing "padding", say, because there's a little "Pa" in the corner.

2) I realize support for CSS is a moving target, but another useful feature would be shaded blocks, representing browser/version, after each property, indicating whether that property is supported / not supported in a particular browser/version.

I think both of these features wouldn't add bulk to the handy guide, but rather, add value.

-Scott
Edmonton, AB