Although there's the directory built into Google Apps, it's not user friendly, hard for the average user to find (open your Contacts, go to Directory and then page through lots of contacts) it did not work as a replacement for the one we had in our on-premise mail solution that we migrated from.
Setting up Cloudpages was a breeze and very easy to configure. I love that I can set access levels as to what information users can edit by OU or by individuals. This meant I could designate HR with the rights to change nearly all features of a user's profile, while restricting the user rights to their own profile. Additionally we added the customization module so we've been able to embed the directory into another website so the users do not need to leave our 'intranet' to be able to search the directory (or update their own profile).
We have also researched the security module portion which allows SSO and customizable login screens, custom password policies, as well as the ability to set Q&A self-service password resets for users. After the New Year we will be implementing that portion as well.
Great product, simple to use, re-brandable, customizable, we're very happy to be using it. And as an academic institution, it's even cheaper for us than the already very low price.