Recently I upgraded from my aging Samsung Galaxy S2 to a Google Nexus 5. Its a massive leap forwards in technology - and a very impressive upgrade. One of the biggest things I wanted to play with was wireless charging.
The Nexus 5 uses the Qi wireless charging standard which uses unidirectional communication using backscatter modulation to talk to the charger at 2kbps. The charging 'transmitter' uses RF at 110kHz–205kHz and received by the Nexus 5 and turned into a suitable voltage to charge the battery.
Initial testing seems to show that both the wireless Qi charger and the wired micro USB charger BOTH charge at around the same rate (averaged over several tests at around 34% per hour).
As far as the actual charger goes - apart from having a UK power supply (19v 1A), the only thing I would improve on this charger is getting the blue LED that indicates that there is a device charging would turn off when the device was fully charged. The Qi charging spec supports this, but it doesn't seem to be implemented in the charging plate.
I really am impressed with wireless charging. I always thought it would be a fad - however the amount of wear this saves the micro-usb port in devices fitted with wireless charging could almost pay for itself over the life of a device - its much cheaper to use a wireless charger than to get a USB port replaced on any kind of device!