The images used in the exhibition are striking, including images of Volantis, Braavos and a version of Harrenhal that's somewhat more epic than what we got on TV. There's also this cool map:
If this maps looks familiar, it's because it's based on the (definitely non-canon) world map I created for my Atlas of Ice and Fire blog a few years back. Although the map should not be taken as definitive, it is cool to see it redrawn by professionals like this.
The exhibition looks really interesting. Hopefully we'll see the artwork in another venue for a wider audience (a book featuring the artwork is part of the Kickstarter, hopefully that will get a wider release later on).