Correct - Aqua does not sync the GAL and not supposed to, it only syncs your personal address book (from the server).
GAL lookup is available through the Contacts app --
-- the Contacts app will ask Aqua to do a "directory" (GAL) search, which it will do, return the data back to Contacts and you'll see it. And if you tap a GAL contact, you will see its details (phone #, physical address, job title, SIP, ...)
If you don't get that, please long press on the account on Aqua's main screen -> Options and Folders -> Exchange options -> make sure that "Sync Contacts" is enabled (checked).