Indeed! I hope they're about as cute as Inkling noises. Afterall, we're probably going to get a bunch of "Booyah!" happy Octolings. Can whatever they say match up with an Inkling randomly saying "Sweaty!"?
The fact that we actually get some lore on the things they didn't explain in the game is something I was always hoping for. When the Zapfish disappeared, me, and a bunch of other people were wishing it was another single player event.
I can see people getting angry that you have to pay an extra $20 to get the complete story, and I understand why they'd be frustrated, but I personally don't mind.
I probably won't be an Octoling myself since I like Inklings too much, but if I can, I'll switch to one on my alt.
When I saw all of the stuff in the Direct, I was actually pretty happy. Not fully for the content itself, but because they put so much emphasis on Splatoon in the Direct. It made me think that maybe Splatoon won't just be kind of an afterthought in Nintendo's minds.
EDIT: I totally forgot to mention another sort of concern with Octolings. WIN/LOSS ANIMATIONS! It would be awesome if they had different win/loss animations than Inklings. I mean, I would still love to see a female Octoling with that goofy grin when winning with Dualies, but a new one would be even better!