I got a DHT22 to replace the DHT11 in my temperature logging thing. It doesn't like me putting the ESP into deep sleep mode: the workaround is to power it from a GPIO so that I can turn it off before entering sleep and turn it back on when I need it. But - when running off 3xAA NiMH, I only get 2.8v from the GPIO pin which is not enough to run the sensor in the first place. Sigh.
Also, don't use GPIO2 on a "Witty Cloud" ESP12F board, it's the tiny blue LED. The DHT11 didn't mind sharing but the DHT22 just won't work when wired to it