Peter Brandt posed a question last week about the Tokina 16-28mm f/2.8 FX wide angle lens. Peter's question was, "wouldn't the Tokina 16-28 be a better lens than the Nikon 14-24mm f/2.8G ED AF-S?" Peter points out that the Tokina 16-28 is less than half the price of the Nikon 14-24mm and for interiors you really don't need the range below 16mm that much. By the way, Peter's question also applies to the Canon world if you compare the Tokina 16-28mm to the Canon EF 16-35mm f/2.8L II .
It's worth noting that the Tokina 16-28mm is designed for full frame cameras. That's what the FX designation stands for.
Ken Rockwell has reviewed the Tokina 16-28 and here's a summary of Ken's findings:
Conclusion: What it boils down to is how important using filters on your ultra-wide lens is to you and how sensitive you are to lens weight. I think Peter is right, the Tokina 16-28mm f/2.8 FX is a pretty good alternative to the top Nikon and Canon ultra-wides.
Update 6/30/2011: As David points out below Ken Rockwell's comparison is not super rigorous. In the comments below there are other reviews that agree with Ken's review but it is not conclusive that the Tokina is as good as the Nikon 14-24mm or the Canon 16-35mm. We would welcome input from anyone that has had a chance to compare the Tokina 16-28mm to the top Nikon and Canon Ultra-wides.