It's a point and click adventure and those have been more or less dead since the mid 90's (there's Sam and Max but I almost always forget about those games). Point and click adventures were some of the biggest games with some of the biggest series before things went to true 3D.
Since these games just don't work well as a 1st or 3rd person game and that's where everything was starting to go, the games died. It also didn't help them much that they really don't work well on consoles since they are point and click.
So yeah, a big point and click adventure from a major publisher is a major deal. If Zack and Wiki does well that means we see more point and click adventures and possibly the return of great games like King's Quest, Quest for Glory, Monkey Island (which I believe this one is based off of-- could be wrong I actually didn't play that series), and all other great point and click adventures.