depend on your luck I guess? haha But well known China Manufacturer has actually got good quality build phones like ZTE or Huawei. Dropped my ZTE from the first floor rolling down the stairs and thup facing down. I tot it would have a spider crack but when I took it up there was only a line of scartch. My phone is even without Gorrila Glass, try that on Gorrila Glass phone
Aside of that as long as there are devs willing to make a ROM for the phone I guess I'm fine with it
Quality Wise, I find it dosen't differ much unless you bought those really really GOOD phone, with replaced interior with sand and a LED light. Then gotta say good luck XD
PS: I do love Samsung phones, their build quality is fine as well. Just think that they should release a line without plastics. For example HTC One and the Xperia Z was one of those great designs ^^
Nothing is perfect I guess? But for long term like you said the issue that I think consumers will face most is sending back for warranty. Time consuming and costy at times.

so how to prevent from being cheated by them? any important measure needed?