It's been said a thousand times in this thread, but wow, this game is addictive. My girlfriend, who would never play a shooter otherwise, cannot put this game down. Since we've gotten it, she has probably played twice as much as I have, and I don't mind at all. It's very entertaining to watch, and it's interesting to see someone approach a map differently than you might approach it.
I am almost level 14, and starting to hit some pretty stiff competition. The level 18s and 20s have maxed out gear, and some of the combinations they put together are intimidating.
From looking at the SplatoonJP twitter feed, it sure looks like their next update will be about Splat Zones being unlocked; the ink-tube was nearly full 13 hours ago on their last update. Looking forward to how chaotic that mode will become!