Well if the mi-one's reviews are anything to go by, the build will be of good quality as the mi-one was said to have a build quality that "matches those from other leading brands, which is a surprise for this price point." and also saying Having used the Xiaomi Phone for over a week, it's definitely left us a great impression: nice build quality and top notch specs for a $310 device. according to engadget's review last year
http://www.engadget.com/2011/09/27/xiaomi-phone-review/ even the brief phone 2's preview by engadget yesterday gave good comments http://www.engadget.com/2012/08/16/xiaomi-phone-2-quad-core/ so i'll wait for the phone to come out before criticizing it.