I don't like all the concepts, but some of them looks really good. I like the weapon designs. If this is real concepts for this game, it will probably end up looking better then what we see here.
I don't like the way Pit looks like in Brawl, it's just so... But I do understand that some people likes him that way. And why should they use a design similar to what we see in Brawl when they did not go with the Link look from Melee in Wind Waker?
Plus, this is a dead gameseries that will see a revival to a new market and to go with something new is not uncommon or to change a character to something almost completely new. If Kid Icarus goes the way these concepts suggest and flops, then Nintendo might revert Pit to his former self again. This might also be something that will work, so pleace hold of untill you will see official art and ingame looks of Pit, the other characters and how the game looks, works, plays and the story before you decide to skip or hate the game.
We don't even know if this art is real concepts or what it will look like beyond early concepts. And most of the people that will buy this game are not the ones that did fall in love with the previous games, people who might never ever have heard about Kid Icarus before. If there will be "Icarus" in the title, then a part of the legacy should be there to, whatever happens.