I love Sigma 35mm 1.4Sigma 35mm is the fastest lens from Sigma Team and works great on Full Frame. It is perfect for low light street shots. I found more keepers from this lens in low light.
Sigma 35mm 1.4 DG HSM is claimed suitable for Travel, Wedding & Events, Portrait and Specialty shoots.

Sigma (Brand) 35mm (focal length) 1.4 (Aperture) DG (Digital) HSM (Hyper Sonic Motor) Art (model) is the flagship lens of Sigma and lens is being praised all around.
The lens comes with a standard Lens Hood and a slightly large Lens case with belt adapter.
Sigma 35mm is made for full frame and can be used with APS-C as well. The lens is compatible with Sigma USB Dock. USB dock is used for 4-stage MAF adjustment and firmware upgrade.

The look and feel of the lens is very solid. It features internal focusing and full time manual control.
The positves:? Solid built and beautiful design, look - feel is good.
? Very fast AF.
? Razor sharp when focused correctly.
? Amazing contrast.
? More keeper from this lens.
? Highly addictive 1.4 range.
? Very attractive pricing.
What expert says:DxOMark "The lens sets a new benchmark for optical performance for a retro-focus lens in this focal length and it?s a feat that?s even more remarkable given the price is well-below that of any of the big name brands."
I used this lens during my Leh trip, Europe trip and few family shot. Here are few shots: Images are not at 100% but it gives idea how the images pop-out on the screen. Close-up portraits are best of its class.

The issues: Everything is fine as long as the shots are within 2 meter. After 2 meter the AF accuracy was varying with distance and as per the light condition on my copy. Further investigation suggested that the AF is inconsistent for different ranges and front focus to back-focus is present in various distances. After various testing and study of my previous shots, I decided to get it repaired from Sigma. I deposited this lens 2 month back and got the money refund. As sigma dealer claimed they cannot calibrate my lens on two bodies at a time. Matter settled after few gracious and respectful phone calls and I liked the attitude of after-sales of Sigma Distributor.
You can read more about focus inconsistency at high aperture at
http://photographylife.com/what-is-focus-shift
Lens is brilliant for close range upto 2m. After 2m, Lens auto-focus issue surfaces. Interested user may find few top results at
http://goo.gl/GLCUhCThe negatives:- You need to find a good copy. But how ?
- You can not do MAF adjustment for varying distance 2m onward through software.
- Only one equipped service center at Chennai.
I will recommend this lens only if you get a good copy and able to get correct AF 10/10 at 1 m to 10m.
I will always miss the Sigma Lens.