I don't drink much green tea, so couldn't really say I went in to it knowing what I was meant to be looking for. It was more "ooh a 10% stout!" and the giddy "it's so lovely, I'm going to walk to work tomorrow so I can have a few" comment from the bar person that made the i-don't-really-want-to-admit-it price a non-factor. I've never paid more for a half, or if I have, it was ~13% and someone had bought me one already so I wasn't counting the pennies.
I think if you didn't know it was a green tea stout, I would suggest an average punter would say "ooh, that's a nice imperial stout. Interesting aftertaste. What is th... ooh another sip. Yum yum".
The bar staff were pretty much freaking out about having it on, but I'm not a discerning punter when it comes to higher abv stouts. They are by definition teh awesome.