Just played for one hour straight and it was awesome! Took me some matches to get into it (they changed the button mappings I think) but after half an hour I was kicking ass and was the top player of my team more often than not. Can't wait for the final version!
Reminds me of Gamescom a few years back when I played Splatoon for the first time and the booth babe asked me for a date because I was good at the game :p Was a really neat demo to say the least!