Apart from looking pretty, the stock Android messaging app is pretty simple and basic in nature. It lacks a lot of features including pop-up notifications, and support for quick reply right from the notification bar.
88sms, a direct port of the CyanogenMod 10.2 messaging app, fixes a lot of issues the stock messaging app, while adding some really useful features.
The app is actually an add-on to the stock messaging app, and does not replace it entirely like GoSMS and other clients. This allows 88sms to remain relatively light in nature and consume less resources.
Below is a quick run-down of some of the most highlighted features of 88sms
Gesture based templates
Optional dark theme
Other minor but useful features in 88sms include the ability to change the vibrate pattern for incoming messages, an option to turn on the screen when a new message arrives and more.
While 88sms will also allow you to send and receive MMS, you might need to setup the MMS settings manually. Also, make sure to disable the notifications of the stock messaging app on your Android device, otherwise you will end up with multiple notifications.
88sms can be downloaded for free from the Play Store.