Mr. Clean wrote in post #2103636
Photozone translates the barrell distortion to a percentage. NOW - that is something to be taken with a grain of salt seeing how the percentage is just ONE lens sample and not historical data of the lens that has been averaged. Still, solid info to go off of!
Just a note - Photozone's tests are done on a 350D, meaning that the results are valid for 1.6X cameras, but not necessarily for full-frame cameras. The extremes of the image circle are more prone to showing distortions.
Personally I think it's the DOF issue. Some samples of potential mis focus have been of canvas type material. You really need to pixel peep to find what threading is OOF! Of a potrait, focus on the nose and wonder why the eyes aren't in focus.
That can be a real issue with any lens, but with a very shallow depth-of-field, technique is essential. The smaller viewfinders on many DSLR cameras doesn't help in selecting the desired focus plane manually.
I don't think it will improve their end product...But it's all assumptions really. Perhaps the 50 1.2 will launch with similar distortion numbers, maybe it will be slower to focus, who know! All in all, it's not my place to suggest how people should spend their money. However, the thread does pose the question "is it worth it"

Yes, that is the question. And the only answer will come when the lens really gets circulated and tested. Canon may have geared this lens to the portrait photographer like the 85/1.2, or it may be an all-purpose low-light "standard" lens with good AF speed, low distortion, good corner sharpness, good bokeh, and good contrast. At any rate, I would expect it to outperform the 50/1.4. If it doesn't, I won't buy it.