For what it's worth...
I did some rudimentary comparison last Saturday. I'm no scientist, but the 14mm looks to me sharper than the Canon 17-40mm at 17mm. My 17-40mm is as sharp as anything I know at near and middle distances, but it seems to fall off at longer distances.
The shots I compared were across a mile-wide river on a cool day using a 5D3 body. It was mid-afternoon in bright sunlight, and I used apertures from f/11 to f/22. Near objects (foreground) distances are comparable sharpness, but the 14mm appears better for the distant objects.
Again, these are entirely non-objective conclusions from a self-proclaimed slow learner!
Oh, and focus can be a challenge with no focus confirmation of any kind (visual or electronic). Using live view you have to manually do what the camera does with AF -- open up your aperture to view the scene, focus, and then go back to your selected aperture to take the picture. Best to review the theory on DOF, hyperfocal distance, circle of confusion, etc.
Overall, it's a beautiful lens for not much money -- and it gives us a tool for trying to get great pictures like Dustin gets!