Justin "You are wrong about how good this lens is" - The 24 1.4 II is in desperate need for an upgrade!! This is not a lens you buy to stop down, this is a lens you buy to be able to use wide open in low lit conditions.
The vignetting I guess is something you to a certain degree must accept. But the level of Chromatic Aberration (purple fringe) this lens produces wide open is absolutely unacceptable.
The worst negative of this lens however is not the CA, but the coma distortion.
I work a lot in night/low light photography, and stars in the edges of this lens get distorted to the level that they look like "bananas". If you shoot wide open in contrasting light sources, eg. night photos of a city, the coma distortion in the edges is so bad that it is ridiculous!
A slight positive is that the 24mm 1.4 from Nikon is not any better. But that still does not mean that this lens from Canon is optically a good lens.
The Samyang 24mm 1.4 which I also own 2 samples of, may not be as sharp in the center as the Canon/Nikon 24, but it is virtually free of CA and coma distortion in the edges, and the Samyang even has more glass/lens elements!! Hence I more often tend to use my Samyang 24 than my Canon 24.
The Canon 24mm 1.4 II, as well as all other of Canons L wide angle primes (14mm 2.8 II/35mm 1.4/50mm 1.4/1.8/1.2) are in desperate need of upgrades! I wish Canon would start to prioritize the wide angle department, and not only focus on tele-lenses.
You're right about the Chroma, it's an issue but not one I've seen drastically reduced in any lens of this focal length. The Sigma 35 may be the best I've seen at equivalent apertures (but that's a different story).
The Canon 24 ƒ/1.4 L II was introduced in 2008, if we can assume a lens nowadays has about a 10-year shelf life I'm not sure you'll see an update from them until 2018.
However, good news is that Sigma is stepping up the competition with their "Art" series - it'd be interesting to see if they tackle 24mm next.
And my bad on the night-time photography, you have more experience in this than I, but I do recall seeing some incredible examples of night-scape photography taken with this lens, which is why I mentioned it.