Replying to Tamron 17-50 f2.8 Thoughts??? K+ for help!

I am looking into buying the Tamron 17-50 f/2.8 and am wondering who has it, what you have shot with it (links to videos would we sweet) and if you think it is work 500$?

This is the link to what I am looking at:
http://www.amazon.com/Tamron-17-50mm-Aspherical-Canon-Cameras/dp/B000FZ3FY8/ref=sr_1_1?ie=UTF8&qid=1425332587&sr=8-1&keywords=17-50+canon

k+ for thoughts
k+ and Good Vibes for videos shot with it


It would be my video lens, for use on a glidecam primarily.