Nice! This review [dpreview.com]
indicates that it has vignetting/barrel distortion issues, though.
IIRC with a Canon/Canon combo the camera autocorrects for this using a saved profile for the lens, which I assume isn't the case with a 3rd party lens.
That Tamron lens looks wicked for someone who regularly goes in and post-processes images - I'm too lazy/busy, though.
the camera only corrects it for jpg. and in raw you have to use canon's dpp for auto correction.
so for people working in raw, it's not much of an issue.