Received a defective one, not working, returned. Bought a cheaper one and it works fine. Can't comment on this one.
Follow up May 8, 2014:
I would like to give Anker a 5 stars because of their customer service.
Anker has the best customer service that I need to give them a great credit. Even I returned the vertical mouse to 鶹 and received a refund, Anker customer service contacted me about my bad experience and offered to ship me a replacement mouse for free to try out. I received the mouse a week ago and it worked fine with my computer. Probably the first one I received happened to be an odd one that could be damaged during shipping. I will look at Anker product first when I shop for accessories in the future.