I am an absolut fan of the ESP8266 in its various forms. It is really cool to build things with it. A device with Wifi, several IO Pins and programmable via C or Arduino is a perfect match for small devices.
The biggest drawback of such a device is: In order for the Wifi to work, you need to connect it to a Wifi Network. In most cases this is the one of your home. So you provide the code with your WIFI SID and passphrase (hardcoded).
If you want to use the device in another WiFi network it needs to be reprogrammed. This is not really portable. Bluetooth for controlling devices is suited way better. You pair the device, then you communicate with it. Bingo.
Espressif must have noticed or they just took the next logical evolutionary step of the their 8266 and created the ESP32. It is more powerful, has more IO lines and bluetooth.
It was long announced. Now you can buy it. So did I. thanx to Watterott I ordered and got 5 of them. Now I am looking for some projects to fit.