Well isn't this a pleasant surprise! I hadn't heard about this game until now, but I think I'm in love. The art style and overall direction looks incredibly charming and lighthearted, which is a nice change from all the grittiness in gaming. I also love how the gameplay instantly reminded me of A Link to the Past which is one of my all-time favorite games.
I'm glad that it's going to be co-op as well, not enough good co-op games these days. I wonder if it will be couch co-op too.