The adapter's plug and play with my MacBook Pro (Model MacBookPro11,2) running OS X Yosemite 10.10.2, but it sometimes loses connectivity from the network and I have to unplug and plug the adapter back in. It doesn't lose its network settings, but I wouldn't be able to ping the router, other machines on the network, or browse the web.
The other major issue is that streaming AirPlay audio from the MacBook Pro to an Apple TV results in stuttering and choppy audio. Here's how it's all connected: [MacBook Pro] -> [Anker Adapter] -> [Gigabit Router/Switch] -> [Apple TV on 10/100 Ethernet]. So the entire setup is connected through Ethernet and the Airplay stream stutters. Wifi streaming on the other hand, appears to be flawless.
How do I know that this issue has something to do with this Ethernet adapter? Because I also have the Apple Thunderbolt Gigabit Ethernet adapter and Airplay works flawlessly.
Someone also mentioned problems when using IPv6. Well I temporarily turned that off and that didn't seem to help either.
Update (18 Mar 2015):
Anker support instructed me to apply a driver patch to OS X here (http://www.ianker.com/support/A7610011), which seems to have resolved the disconnects and Airplay stuttering. From the looks of it, the adapter was using OS X's built-in Realtek drivers which were probably outdated or not optimized for Anker adapter. After applying the patch, Network Utility no longer identifies the adapter (en5) as an Apple adapter, but of Vendor: Realtek and Model: Realtek USB GBE Family Controller. The adapter appears stable, Airplay is stutter-free, and LAN transfers are very fast. Definitely a much better value and more universal than purchasing the Apple Thunderbolt Ethernet Adapter for $29. But OS X users are strongly encouraged to apply the driver patch for best performance.