I've never had a mobile phone with a decent camera. I would never use a phone instead of a camera - they don't quite live up to my Sonys or Nikons but I have recently had a feeling my phone seemed to be getting even worse than I remembered, which was seriously annoying me.
Then I suddenly realized the decline in quality coincided with my buying a protective case so my touch screen didn't degenerate before the end of my two year contract! I took it off to test my theory, and what do you know! Bingo. It seems the thickness of the case is blocking some of the light from entering my camera lens.