Remember that neat Twitter client from earlier today called Talon? Well, the developers have also released a new SMS app called EvolveSMS with a lot of the same UI flair. EvolveSMS takes advantage of translucent system elements on KitKat and borrows some extra pieces from Google's design language to create something very cool.
Klinker Apps previously created a popular SMS client known as Sliding Messaging. EvolveSMS is essentially a spruced up version of that app with improved features. It utilizes a blurred profile image effect in the header of each conversation, a look that developer Jacob Klinker says was inspired by the last big Google Wallet update. When KitKat was announced with transparent navigation and status bars, Klinker thought that went along well with the in-process UI. Some people (myself included) have expressed concern about the way the status bar hides in Talon. The approach in EvolveSMS seems more consistent, at least based on my initial impression.
EvolveSMS does all the usual SMS stuff for free (plus widgets!), but there are a few in-app purchases in the settings to add additional features. The $0.99 customization pack includes themes, night mode, and contact avatar tools. The feature pack is a bit more expensive at $1.49, but it adds Dropbox backups, expanded MMS functionality, scheduled messaging, and more. This app needs to be set as your default SMS client if you've been using Hangouts on KitKat, and it might be pretty and feature-packed enough to convince some people to do just that.