The ESP8266 alone has just one analog pin, that is limited to 1v, which is far from useful for most applications.
Battery management would make it also way more useful as a "thing". I know that right now i can run the board with 3AA or a litium based battery, but there isn't a way to check battery voltage, or recharge it.
If 8 bits precision is enough, you can also use an PCF8591, an I2C ADC/DAC, it provides 4 inputs and 1 output.
And, since this PCF8591 has I2C addresses, you can use multiples of those on the same I2C bus.
Give 2 analog pins for A0: one direct connection (0-1V range), and the second one with voltage divisor (1-5V range). (or use 1 pin + jumper selection)
Use 800 mA or 1Amp 3.3V LDO (ESP use lot of current, neopixel use lot, rfid use lot, we need power !)
Create some shields/addon boards (like the arduino) for sensors board, battery board, ...
Integrate a PCF8591 could be a very good thing to build wireless sensors.