I had trouble getting GPIO4 and 5 to work properly on the board. I looked at the GPIO pinout for the ESP8266 and followed the traces for the GPIOs and they looked correct.
I found out from some Googling that some variants of the ESP8266 (ESP-12E?) have switched GPIO4 and 5 around, so I checked on my pHAT and that appears to be the problem.
I just wanted to post here because the solution was not very easy to Google. Would also be cool if you guys could put a note somewhere on the website or switch the labels around for the next batch you make.