In principle, the charger works as described, as far as I could test it. The two ports are wired differently and thus allow different devices to recognize the adapter as a charger correctly. My Samsung Galaxy Nexus for example detects only one of the ports as a charger and would invite the other port only 500 mA.
Unfortunately I have to return the item, because it interferes with radio reception in my car. How big is the disturbing influence, seems very individually by radio and car depend, as other users (in other chargers) have no interference. Those who have weak reception or störempfindliches Radio, maybe is not happy with this adapter.
I tested two more charging adapter, so that I can compare it.
EasyAcc Dual USB output (5V / 2A & 5V / 2A) car charger
much more massive disturbances, partly I could only hear noise
Nokia DC-20 Car Charger with 2 USB ports and 2 USB cable for Lumia 800
no disturbances, but "only" 2x 1 A charging current according to the manufacturer