"So, where are the complaints of Samsung's handsets?"
My Galaxy S4 (still going strong, I expect to get a few more years out of it) developed a bit of burn-in that I noticed a year or so ago. It's noticeable and a little annoying, but not catastrophic. If, however, it had developed the issue within a year or two of my getting the phone, then I would have considered that an unacceptable fault.