i bought that lens along the Tamron 18-250 for multi-use lens and both are great from my point of view..... I'm waiting to use the 17-50 f/2.8 in Munich, Germany at Night because i tried it indoor and it's really great and affordable (a bit heavy "but it helped keeping my hand steady:roll:")
Yes, it is not a small lens, but the results it gives are quite nice.
I'm not generally a big fan of wide angle lenses. I don't care for the perspective, and usually perfer to shoot at longer focal lengths. The 17-50mm zoom range gives me a moderate telephoto for most of my shots, plus a good wide angle when I need it, all with a maxximum aperture of f/2.8, satisfying my 'available light' fetish! It's my favorite lens.