Navigation button circle is not fixed well - it shakes when you walk or move and you hear annoying knock-knock-like sound. I had to fix it myself by removing the navigation button, putting inside a soft 3M layer cut in a circle shape and putting the nav-button back . The good news is that this was quite easy. The concern is that I should not do it myself but the manufacturer could put that 0.001$ noice-removal layer instead of me. That's shame.
very good ^^