So I just came back from a very long meet. We've been playing an American version of smash 4 for the past few days or so because as if we were going to wait till the Australian release. There is so much I would like to say about the game, but there is one interesting observation in particular that I'd like to share.
Basically, there are characters that got huge buffs in smash 4, not because of any change in their move-set, or speed of attacks, or recovery etc necessarily, but simply because they work better as a character in the smash 4 game. Link and Toon fall into this category. For now though, take Fox for example. Oh sure he got a buff to his recovery by being able to act out of side-b (eventually), but on the whole, looking at just the character Fox in Brawl and in smash 4 and disregarding anything else for now, he actually got very nerffed in general (Dair, Fair, U-smash, U-tilt, Laser and Shine), and yet, Fox as a character in smash 4 is considered one of the best characters. The reasons for this have nothing to do with the differences made to the character; it's because of the fact that smash 4 is a different game and it just so happens to work in his favour. There are the obvious things like the fact that there is more hitstun which means that all the strings of attacks that felt like they should have worked in brawl now actually combo, and then there's the fact that Fox no longer has to worry about ******** matchups with stuff like the pikachu chaingrabs.
As for the Links, I found that one huge difference that has generally been overlooked is the fact that airdodges have been nerffed in smash 4, which means that their spam game in general is insane now. Being able to have multiple projectiles out at the same time while the opponent isn't able to just airdodge through it or airdodge to avoid getting hit again once they get hit by the first projectile makes frame traps, kill setups and camping so much easier. And this is without mentioning the more obvious benefits of smash 4 like the hitstun and the ledge mechanics.
Other examples of characters that greatly benefit from simply being in smash 4 include Ness because of the ledge mechanics and the rage mechanic, but the point is, you need to look further than whether or not any particular character is better than a previous version of that character because in many cases the all important factors will come from the differences in the game in which those characters find themselves.
I'm not sure how well that was all worded, but there it is.