Excerpt: The Canon TS-E 17mm f/4L Tilt-Shift Lens was introduced at the same time as the Canon TS-E 24mm f/3.5L II Tilt-Shift Lens. Because of their similarities, I am borrowing some of the material/layout/text from the Canon TS-E 24mm f/3.5L II Tilt-Shift Lens review for the Canon TS-E 17mm f/4L Tilt-Shift Lens Review.
Conclusion: The Canon TS-E 17mm f/4 L is an amazing lens although beginners will struggle to master its possibilities at once. When using the lens based on conventional settings it behaves pretty much like a normal ultra-wide prime lens. The center performance is pretty much excellent followed by good borders/corners at f/4. At medium aperture settings it's very sharp across the frame. The level of barrel distortions is unusually low.