The Sigma 24-35mm f/2 Art series lens is the first f/2 zoom for DSLRs, and it has certainly sparked a lot of debate about it's usability with such a short zoom range. I think the lens is basically 3 faster primes in one lens, 24mm, 28mm and 35mm. For the people that need this range of focal lengths, this lens could be a game changer. For the rest of us? maybe not. However, it's nice to see a lens manufacturer push into new territory.
Bryan over at The-Digital-Picture has completed his review of the lens and came away very impressed.
Do wide angle focal lengths work for some of your applications? Need apertures wider than f/2.8 to stop action in low light, to allow handholding in low light and to create a stronger, subject-isolating background blur? Need a range of focal lengths available at your fingertips without a lens change? The Sigma 24-35mm f/2 DG HSM Art Lens could become a most-frequently-used member of your kit. Read the full review