Might sound stupid, but have you taken the plastic cover off the camera lens? Or tried wiping/cleaning it?
A bad error on the phone settings is, when you change something, you have to do one at a time and save after each ie. change image size - save, change image quality - save etc. For some reason, if you go and change a few things at once, then save, it wouldn't have saved all the settings you did. I heard about this on a youtube review video of the phone, and tested it myself to be true. Have you perhaps saved some settings in this way but infact nothing has changed? Just a suggestion though
Mine seems to take pretty good pictures, but is no way as good as my digital camera, which is 7mp, but nonetheless, shouldn't be 'THAT' different.