At the price I had to pay in bundle with NEX-5 it is a bargain. However Panasonic shows that it could be made way better with it's Lumix G F1,7/ 20 mm
produces a slight amount of pincushion distortion (~0.6%) which is usually not objectionable in field conditions; At f/8 it is working very good all over the image field
the corner performance is rather poor especially at f/2.8 and f/4; The fairly heavy amount of lateral CAs isn't helpful