Really cool. I went to this expo for 2 years, I find it interesting for the general public, while most of the exhibitions at COEX are more targeted to industry experts.
They also hold the World barista contest, and you can see baristas creating cool art on lattes. they were all korean though, i don't know how international they were.
you can try some expresso shots and americanos, and a lot of juice, syrups and teas.
you can also buy a lot