BiteSMS is a full replacement for the iOS Message app. It features many extra featurings including Quick Reply, Quick Compose, Scheduled Messages, Auto-Forward, Passcode Lock, Privacy, Contact Pics, Easy Pick Smileys, Templates, Signatures, Delayed Sending, Themes and much more!
You can get the app free from the Big Boss Cydia Repository. After 7 days a 'small' ad will be shown. You can purchase a license for $7.99 to prevent the ads.
Check out the screenshots below or head to Cydia to install the app. If you haven't jailbroken your device, you can find instructions on how to do so at the iClarified Jailbreak Wizard.