While the picture doesn't really give you a sense of the scale of the cup, it measures 9.84" H x 12" W (with handle) and carries a hefty price tag of $94.95.
At 138 ounces, the mug is big enough to fill up with a little over eight Grandes (their 16-oz cup size). Interestingly, it isn't biggest cup Starbucks has ever offered. Last year, they offered the the Big Logo Mug measuring 14.57" H x 15.75" W (with handle) over in Japan (pictured below). Also, apparently, back in 2001, for their 30th anniversary, they put out 1,000 5-gallon (640 oz) mugs for promotional display.
Photos via Starbucks & Starbucks Japan, respectively.