Eh, that clip doesn't show anything similar to the squid mechanic, or the roller, plus the level design is completely different. Splatoon has about as much in common with that as that has in common with Super Mario Sunshine.
The only thing unique about Splatoon is they want $60. That is insane. Oh, plus 3 dolls for another $45. Its not DLC just dolls.
Also they really just took concepts of De Blob and made it into a shooter.
I'm not sure that's fair. It has a lot of originality, especially compared to a lot of multiplayer shooters today, we don't know how much content is in it, and the Amiibos all come with different challenge levels, mini-games, gear, and the three pack is $30. As for the De Blob comparison, the mechanic of taking over territory by painting it dates back to old Mario Party minigames - Splatoon simply expands on those ideas.
I'm really not getting the negativity around this game.