Yes, you’ll still need to use a regulator if the rest of your project is running at 5V, but if the pins are 5V tolerant, interfacing the ESP8266 with a variety of hardware becomes very easy.
What can’t the little $5 WiFi module do? Now that [lhartmann] has got an ESP8266 controlling the motors of a 3D printer, that’s one more item to check off the list. What’s coolest about this ...