I think Banjo and Sora are the only cases where the most hardcore fans were being served what they wanted. Steve being the actualy most iconic character to get in (even though I haven't even played minecraft at all).
Most other DLC characters were kinda odd choices, though I think Terry was a cool underdog supprise. Him still being the icon of his own series, but more obscure than the rest nonetheless.
All in all, I wouldn't have picked Sora myself (would've rather picked Donald in his KH outfit, but whatevah). But he looks like a far more interresting swordfighter than that whole edgelordy Fire Emblem J-pop band combined.
There was only one big letdown from Sora, that was his reveal trailer. Sure, it's packed with a lot of poetic-jibberish-symbolism (fitting for a character from a game with an insanely convoluted storyline). It also looked all 'Final Fantasy cutscene pretty' that was nice too. But man, was that reveal trailer BORING AS FUUUUUUCK. Pretty much every DLC character had some cool action-packed or funny video made for them. But Sora just calmy floats out of his keyhole, with some fabulous glitter blowing out of his bumhole, catches his keyblade and says letsgo, then shakes Mario's hand like big polliticians do at some press converrence.
Like, that's it!? That is the big reveal trailer for the final character? At least the character looked well develloped in his gameplay footage, wich is the most important part anyway.