The ultimate winter runabout? Perhaps. A compromised sports car? mmm....perhapser. If you're living in an urban area with decent snow clearing, and you already have a wagon/suv for weekend trips to the cabin then, yes, this would be a good winter runabout.
But in actuality, if you already owned a wagon/SUV, why not skip this and go right for the boxster? With winter tires, the mid-engined porsche is supposed to handlle quite well in the white stuff, and my guess is it'll drive noticeably better than the Audi in the dry. Let's not forget the boxster's extra dollop of practicality, thanks to the front trunk.
Granted, the TTS has AWD, but it's so low to the ground that it will likely bottom out in more than a couple of inches of snow, making it not much better than any other low-slung sports coupe. Ground clearance issues aside, i'm sure the drivetrain would make for a great daily driver, but it would be more enticing for me in a 3- or 5-door S3 flavor.