Sigma 17-70 f2.8-4 DC MACRO OS HSM

I'm no longer satisfied with the 18-55 kit lens on my a55 and want to upgrade. I've been debating the pros and cons of the Tamron 17-50, Sony 16-105, and CZ 16-80 over the last few days, and then Henry's Canada goes and puts their Sigma lenses on sale.

I'm very interested in the Sigma 17-70. The OS would be great for taking movies on the a55, as would the HSM. It's faster than the Sony and CZ, and longer than the Tammy. The price is right too - right in between the Tammy and the Sony.

My only problem is a lack of references for it. Dyxum only has 4 reviews. I've Googled other reviews and while they're positive, they're all for the Canon/Nikon versions. I'm a bit wary of generalizing that to the Alpha mount version even though I know it's basically the same lens.

So my questions out to the crowd are: have you used this lens? How is it? How sharp is it? Would you recommend it?