FINALLY I get to post - my stupid internet has been derping constantly lately, and ever since Nintendo Direct, I've been looking forward to seeing what people were saying about it. I know I'm very late on the bandwagon here, but I'll go ahead and express my thoughts:
I'm probably one of the few people here who is happy with Zelda and Sheik being separate characters. I'll explain why. But first, I want to say that the concept of having the option to transform into another character is interesting, as Fujin pointed out, and one of the things that made Zelda unique. I would have loved to keep having this option throughout Smash games... if Sakurai didn't make such a big flop out of them. This can be noted with Samus and ZSS as well; one character being significantly 'better' than the other, while the other is lucky to even have someone use her. Pokemon Trainer, also another huge mess; along with the fatigue, no one ever bothered with some of the Pokemon, or just tried to stay Squirtle as much as they could. Finally, we have Zelda and Sheik, who share similar boats as the case with ZSS and Samus.
So my point is, if Sakurai COULD make each transforming character actually viable, I would love having Zelda and Sheik together as one character. But seeing as he's yet to show this yet, I am content with having Zelda and Sheik by themselves. At least the two characters can get another move to use to replace Transform (especially for those that only used one character or the other). And on top of that, those of us that accidentally use down b, we won't be put in a bad spot.
Now as for Phantom, I can see how people aren't pleased with replacing an entire moveset (Sheik) with this move, but again, just goes back to what I was saying about them each getting a move now (like Sheik getting the 'grenade' move). It does look like Phantom has some start-up time, and I was also reminded a little of Din's Fire, but can't really say much until I actually see more footage of the move, or try it myself. If it actually stayed out for awhile, that could pose some interesting defensive options for Zelda, but if it's a move that hits like a smash, then it's hard for me to see people getting hit by that. We'll see though. Also, randomly reminds me of dark magic with all the purple when Zelda summons it... she must have been taking Conjuration training from someone ^^
For the rest of her moves, I didn't see anything significant that's worth mentioning. Some of you said her Up B seemed faster... I hope that's true. I also wonder if both of her Fair and Bair will be the same again, or if they plan on changing one of them?
Anywhos, got to stop for now, before my internet derps again.