The downside is that a quick - charging compatible charger doesn't come in the box. (digitaltrends.com)
There are some wireless charging companies offering compatible chargers but these are not endorsed by the manufacturer and could damage your smartphone. (carphonewarehouse.com)
That's because the current implementation maxes out at 5W, even though the Qi standard itself will handle more power with compatible chargers. (slashgear.com)