10 out of 10 points and recommendedGreat utiliy regarding minimal size and weight. Very good image quality. Effective image stabilization.Performance open at 15 mm (weak corners). Prone to lens flare, use lens hood. Small apertures, difficult to isolate subjects.
I bought this lens as a kit with the M3 together with a Bilora UV filter, a 16 GB Sandisk card and a Tamrac pouch for 500 Euro (ca. 560 US$). If it was the idea of the engineers to offer maximum value with minimal size, then this has been well achieved. The lens covers the focal range I use for 90% of my fotos. It is really small, much smaller and lighter than the 18-55 kit lens, protruding just 45 mm out of the M3. It is made from plastic, however, it is functional and build quality is more than OK regarding its size, weight and price.reviewed October 15th, 2016 (purchased for $100)
Image quality was surprisingly good. I made raw pictures of my bookshelf at 15 mm, 24 mm and 45 mm at f/6.3 and f/8 (Iso 100) and compared them with raw pics I made in parallel with my Nikon D610 with the 24-85 mm kit zoom at f/8 and corresponding focal lenghts (Iso 100). I then corrected all files in DXO (standard settings including correction of vignetting and distortion) with manual correction of WB and exposure and with the same color output (Canon 6D profile). I carefully compared all files on a 5K Retina iMac and printed some of them at 30x45cm (A3+) on an Epson SC-P600. From a normal viewing distance or at smaller print sizes it was barely possible for me to decide which picture was made by which camera. Yes, viewed from 10 cm distance, i could see a very slight difference in sharpness and contrast in favor of the D610/24-85 combo, but this was minimal and only visible in the side-by-side comparison. The visible difference was not greater in the corners. When I sharpened the M3/15-45 pics a little bit more in DXO (Lens softness module e.g. +0.7, Detail 60) the difference in the 30x45 prints was gone. Under the conditions mentioned I am perfectly happy with the IQ at printing sizes up to 30x45 cm. IQ wide open at 15 mm was not so good (weak corners), however, most often I use f/8 or f/11 for landscape pictures, and - when sharpened with DXO (e.g. +2.0) - 30x45 prints from pics made with 15mm f/3.5 were fully usible.
From my rather preliminary and non-professional tests I conclude that for practical use with prints up to A3+ and in combination with DXO there is no real limitation in image quality using the M3/15-45 - even at its weakest spot (15mm wide open).
I was surprised how minimal the differences in IQ were compared to a FF DSLR. I have learned that IQ differences in lab tests obviously occur on a very high level (at least for a hobbyist like me) and that I have overrated the differences described in lab tests for practical use with the smaller print sizes I use.
The image stabilisation is quite effective and compensates well for the small apertures - I can get good results at 1/4s. So I can take useful pictures at 1/4s, f/4 and Iso 3200 (EV 1) without tripod which - in such a small packet - is something I have dreamed of for years. In many situations the 15-45 might be more useful in low light than the 22 mm f/2 which is not stabilized. On the negative side, the lens is prone to flare, so one should use a lens hood or give shadow with the hand. Due to the small apertures it is difficult to isolate subjects.
In summary, one really gets a lot from this lens (image quality, stabilization, focal range) regarding its size, weight and price, and it is quite easy to circumvent its major weak points. I do not have to worry about image quality when I go out with my M3/15-45.