The demo/Global Testfire was amazing. I had an absolute blast playing the game and I'm really excited for its release. I'm so happy to finally have a shooter game that appeals to me, as it's not focused on things like head-shotting/killing other people to get ahead. In fact, Splatoon doesn't even give you props for doing it. It's all about that turf. B)
I'm also pretty psyched to hear that they'll be offering more and more DLC maps every few weeks. I think that's a great way to keep things fresh. I have a feeling at the least the first few will likely be free, too. (Though I can't say for sure, but I think they're doing their best to promote the game as much as they can, and free DLC will help with that.)
The only thing that has me a little bummed is that creating your own matches with friends won't be available until August, apparently. I feel that's something they should have ready at launch, but I guess after Global Testfire, maybe they just found they have more to perfect before they do that. Either way, it'll make streams a little lackluster for awhile, since I was looking forward to playing with friends off the bat.
Definitely hyped, though. Nintendo is really bringing it this year and I think it's only the beginning. I'm excited to see what more is in store with E3.