The objective with my pen camera delivers very good and sharp images, even at maximum aperture. What on the lens a little bothers me is the distortion that is a bit larger compared to the Sigma 30 / 2.8. However, you can hardly see the distortion in jepg.
And yet what I found funny that when the lens is removed from the camera, you can hear when you move the lens a funny (rattling) noise. This sound is normal when the lens (I think at least) because my Sigma 30 / 2.8 and this produces noise when moving. However, it is not a malfunction (as I've read at least on the website of the manufacturer).
Conclusion:
From me the Sigma 19 / 2.8 is a strong buy recommendation.