Since Android 4.4′s release, the SMS application was officially removed from Nexus devices and replaced with Hangouts. This does not mean that SMS applications are dead and no longer supported—nothing could be more wrong. They are doing just fine, with more and more applications available in the Play Store.
One of the newest and most interesting SMS clients was recently presented by XDA Senior Member klinkdawg. What makes EvolveSMS so special? It has a very nice UI, with various swipe gestures. Contacts are visible on the slide-in menu, and messages in the main window of the application. This application supports group conversations, popups, and lockscreen widgets. The developer also took care of security, so messages can be archived and password protected. EvolveSMS also has full support of Emoji, Android Smileys, and those found in iOS7. The application is free, but if you want to support the developer, there are plugins that unlock unique features. Some elements of this application are open source, so if you are a developer and would like to give some code insight, please visit Github repositories.
If you are interested in good looking and functional SMS client, you should definitely visit the application thread and give EvolveSMS a shot.