ok, i have asked the same question at allaboutsymbian.com/forum, and a guy named munkiii said

"I have one on my N95 (not 8gb), best case i've tried. had mine on for about 3 months now without any problems. Although i do think it's time i bought a new one cause of a slight chip in the bottom corner (on the inner plastic part). But for that cheap of a price, i'd buy one every month if i needed."

seems it is not a bad one.........