DxOmark's review of the Sigma 24mm f/1.4 A - highly favorable

[Aglet]

Quoted excerpt from their conclusion:

".. the Sigma has more uniform performance overall, including superior control of CA and distortion. It’s a worthy addition to the range and will only add to the maker’s reputation. Plus at around half the price of the Canon.."

www.dxomark.com/Reviews/Sigma-24mm-F1.4-DG-HSM-A-Canon-EF-review-Better-by-design/Conclusion

Sounds like Sigma's gonna show the OEMs how to make mainstream lenses and leave Canon to what they're really good at, niche products.
Apparently Sigma's patented a 400/2.8 as well. Last time I spoke to a Sigma rep they sounded like they were gonna put more effort into primes.
I've only purchased one MFT Sigma prime, the 60mm f/2.8. it's a smokin' hot performance for $200!

EDIT; yup, if you need to shoot a 24mm wide open, the Sigma wins. by f/2.8 they're about the same for sharpness. Could use some bokeh comparison tho. :-\

 

[Mt Spokane Photography]

Although I will not buy Sigma (for Canon) due to past problems, its good to have competition. I have lots of vintage film cameras and lenses, including OEM and third party. Virtually none of the old third party lenses will function when I get them, time has been very unfriendly to them. On the other hand, most Canon lenses are fine (Only one had a issue out of many dozens), 60% of the Nikon lenses work well, and about 20% of the Minolta lenses (AF lenses were the worst as expected). Its almost always a matter of lubrication.