The issue is reliability. There are no reviews, but spinning hard drives are horrible for reliability. Drop it while its reading or writing, and its toast. A SSD unit would be better in that respect.
I saw nothing about the transfer speed either what Wi-Fi protocols does it use?
The field is full of similar devices, so what is its advantage?
http://www.amazon.com/Passport-Wireless-Portable-External-Drive/dp/B00M9B4482/ref=sr_1_1?ie=UTF8&qid=1450930616&sr=8-1&keywords=wi-fi+portable+hard+drive
http://www.amazon.com/Seagate-Wireless-Portable-Built--STCV2000100/dp/B00JSQV44S/ref=sr_1_2?ie=UTF8&qid=1450930676&sr=8-2&keywords=wi-fi+portable+hard+drive
http://www.amazon.com/Patriot-Wireless-Mobile-Drive-PCGTW1000S/dp/B00BUMXO3C/ref=sr_1_5?s=pc&ie=UTF8&qid=1450930889&sr=1-5&keywords=wi-fi+portable+hard+drive&refinements=p_n_feature_five_browse-bin%3A2419645011%2Cp_n_feature_two_browse-bin%3A5446812011