These covers DO fit Samsung Galaxy SII perfectly. Those who claim that they don't are obviously putting them on wrong or putting them on a phone which is not a SII. They last for a long time - I have only used two in the few months I have had my phone. The first one was wasted by my own fault - I put it on wrong (too far to the left) and so it gathered dust. If you ensure your device, room and hands are free of hairs, dust and dirt, and take your time putting these on your phone, there is no reason why they would not fit and stick.
My phone has been through the wars with being carried around in my bag all the time, and the screen cover itself remains scratch free! These are high quality for the cheap price.
Each cover comes with it's own little polisher also, which allows your phone to keep safe and clean.