This isn’t an ESP8266 shield, either: you can write code for the ESP module, connect the serial pins, and hit the program button. The basic functions of the Arduino IDE – pinMode, digitalRead ...
If you already have a ton of smart home devices and you're wondering what to do next, I recommend picking up an ESP8266.
Arduino has a library for quickly and easily ... There are also much more advanced techniques for saving power on ESP8266-based boards; from boards that barely sip a single microamp while sleeping ...