The Canon EF 35mm f2 is a no frills lens. It has a P-MPix score of 15. This resolutionsharpness score is mid range for a lens of this focal length and the scores for most of the measurements bear this out. The overall DxOMark score of 22 does trail behind its competition but it is respectable for such a cheap lens.
Alongside the Samyang 35mm f1.4 AS USM and the Carl Zeiss 35mm f2 ZE which are the closest in price and specification respectively: there is not much to choose between them, but the Canon has higher resolutionsharpness than the Samyang and has lower distortion than the Zeiss and neither of the independent lenses has autofocus.
The Canon lens is not without faults: wide open both resolutionsharpness and vignetting are quite poor, resolutionsharpness down to around 40% in the corners and vignetting nearly 2 stops.
Both of these measures improve rapidly when the lens is stopped down, even by just one stop. It would also be fair to mention that most of the 35mm lenses tested by DxOMark for Canon have similar characteristics for vignetting and all of the others tested are much more expensive.
Transmission at 0.3EV, distortion at .3% and chromatic aberration at 9µm are all well controlled and the Canon does not stand out either way against its competition.