Canon's very wide angle lenses do not enjoy a good reputation, especially against the Nikon or Carl Zeiss counterparts. This is especially true for consumer version of the wide angle lenses. I do not have experience with the other wide angle lenses, but I have tried a EF 24mm F1.4L, and now own a 35mm F1.4L. Both are exceptionally good lenses, despite what others say. I believe the 24mm F1.4L is the only auto focus lens in this focal length and maximum aperture.
The 24mm F1.4L I tried had problems with the compound that binds the lens elements together. It had thousands of little bubbles inside, but man, even with that, the lens was SHARP!!! And the focus was dead on, even on my 10D. Despite the great image quality of the 24L, I could not justify $1000CAD for a lens that has bubbles inside.
When Kal from Henry's called and told me he had a used 35L in good condition, I went for it, and I am glad I bought it.
The lens turns out to be everything other owners have said. Very sharp, and great colours. But then again, more than a few people are saying the lens is over priced, especially compared to the EF 35mm F2, which is optically very similar to the 35L. I had chance to compare the two lenses, and my point of view is that, yes, the 35mm F2 is a very good lens for the price, and optically both are excellent, but when you see them side by side, it's like a midget standing next to the Green Giant. The build quality of the 35L is days & nights better than the 35mm F2. It's a tough decision which one to keep, but I ended up keeping the 35L. You can see the comparisions here: