There isn't a whole lot that is special about the Nexus charger, but it does have some interesting things about it. First off, it is compatible with the Nexus 4, 5, 10, and both models of Nexus 7. Second, it offers 9 watts of charging power, which should mean a bit faster charging times on the phones. It is unclear if it would change the times for the tablets, since the OG Nexus 7 shipped with a 10W charger. Third, unlike many wall chargers, it isn't a combo of a brick and a USB cable, it is one single unit. This means if the cable breaks, you need to replace the whole thing.
Also, it should be noted that there is a fair chance that this is the same brick charger that comes with the Nexus Wireless Charger. Of course, the Wireless Charger would cost you $50, whereas this cord alone is only $15 plus shipping, so there is a solid difference in price.
source: Google Play