It's much better than Control Stick up for jumping. Easier to pull off short hops this way, too.
I feel like it has a similar dynamic for me at least. As long as I can hit jump with the top of my thumb and roll down to the middle of it to hit A, then it feels good enough for me. And technically you can do the same thing with B and Y now to do up B out of shield if you need to (though I'd still feel more comfortable using L to jump for that anyways). Plus I can't use tap jump anymore ever since Brawl allowed me to not have to. Would just always make me jump when I don't actually want to if I did.
Hmmm, guess I just didn't practice enough. It's too late for me to unlearn tapping up now, I'll have to wait for the Wii U version. I kept screwing up in the 3DS demo, I'd hit A instead of X to jump because I'm used to X being on the upper-right of A instead of upper-left. Definitely struggling with short-hops on the control stick though.