iPhone
Will this work with an old 4S iPhone?
Yes. Just download the app and you're set. Do document yourself as it is not as simple to use as you would think. Most negative comments come from people not being able to connect the device to their phones, because:
a) They think it works like bluetooth. IT IS NOT BT...
b) You must connect your WIFI to it. Don't expect an auto-connection
c) Make sure the wireless of the stick is on and blinking