DxOmark tested the Leica M10 sensor and the conclusion isn’t that exciting:
For pure sensor performance, the Leica M10’s 24Mp CMOS chip is in the same ballpark as recent Leica full-frame chips. Its odd behavior for both color and dynamic range is worth looking out for, and it’s fair to say that although sensor quality is good, it could be improved with better implementation. Compared to the top-performing full-frame sensors we’ve tested, the M10 lags a little behind at base ISO and throughout the sensitivity range, with image quality more in line with the best APS-C chips. So better image quality is available and the M10 isn’t cheap, but first-class engineering that meets the Leica standard never is. However, a digital camera with similar proportions to analog M cameras will be hugely appealing to Leica enthusiasts. Add to that compatibility with almost all Leica lenses ever made, as well as its simplicity of operation, and the M10 will be an attractive proposition to those who appreciate the quality of the Leica system.