A glass full goes for $4.59 but I received this courtesy of Smashburger.
In addition to the glass-full, you also get whatever is left over in the metal mixing cup, which is about enough for another 3/4 of a glass-full (although it doesn't look like it in the picture; then again, it's not a huge glass and is tall but narrow).
Other than the general lack of mintiness, the shake was thick but easily drinkable. There's the distinctive vanilla bean flavor to it and a richer, creamier base from the Haagen-Dazs ice cream.
Overall, Smashburger's Mint Oreo Shake offers a rich and creamy shake experience. The base itself was great but the mint and Oreo pieces were a little lacking (a fixable problem, as you can just ask for more syrup and cookie bits if you're eating in anyway).