The iPhone has been accused of having a disappointing camera with Apple choosing not to enter the pixel-count race. For me, that makes it a great sketchbook. If you're out for a walk and have sloppily not got a 'real' camera with you, the iPhone lets you sketch the shot you'll take for real when you return. Or, depending on how you feel, its weaknesses can be turned to strengths. It does colour very interestingly, nearly always underexposes 3/4 of a stop and has terrible ergonomics but, but, but... I like it.