The new feature is especially useful if your search includes advanced operators like to: or from: because it's easier to enter the sender or the recipient.
Since Gmail doesn't show in the list of suggestions previous queries or common patterns from your messages, the feature has a limited use. You could get similar suggestions by typing names in the Gmail chat box and clicking on "View recent conversations".
Some other search-related Labs feature you should enable: Quick Links, which lets you bookmark Gmail pages, including frequent searches, Go to label, that autocompletes the name of a Gmail label, and Multiple Inboxes, which allows you to create a dashboard from different Gmail views.
Another quick way to view your contacts is to use the standalone page for Google Contacts available at google.com/contacts or google.com/contacts/a/domain.com. According to the Apps Update blog, "the new standalone contact manager allows you to manage your contacts within Google Apps without enabling Gmail". You can also use it with a regular Google account that doesn't include access to Gmail.
{ Thanks, Niranjan and Jason Varitek Fan. }