1 - I didn't break the bank or have to mortgage my house to buy a Fuji x-100, or Leica M6 or something similar. I found this little gem second hand in great condition.
2 - It's so inconspicuous, I am photographing in peoples faces and they don't realise (great for candid, un-posed shots).
3 - In camera contrast control and very easy to find/change.
4 - Fixed 28mm wide angle is perfect for grabbing a lot of information and forces me to get in close to the subject.