You may at times need to get your hands on a specific SMS to confirm information about an appointment or get together with friends.
Rather than looking through all of your SMS messages until you find the right one – something which may be arduous if you store a lot of messages in the phones memory, why not instead use the search engine to perform the search for you?
Once on the main page of the "Messages" application, you simply need to drag the display to the top of the screen to see the search field appear.

In this search field, you simply then need to enter the key words which will allow you to instantly find the message you are looking for, and its corresponding information.

Since the function is already present, it would be a shame not to use it.