Well, to sort of list it:
* Her grab is nearly 2 times slower to connect then 90% of the game's grabs.
* She arguably has the worst overall mobility in the game, and basically loses to Dash Dance camping.
* TALL AND FLOATY. Gets KO'ed very early, but has a larger hit-box than most other floaties.
* Overall, her moveset was poorly design outside of 3-5 moves.
Jab, Fsmash, Usmash, and NAir cannot really be relied upon (in non 1.0 versions) because they can be SDI'ed (Smash directional influenced) out of making them not fully connect. Ftilt and Utilt are very small ranged and slow, AND don't offer much reward for hitting with, Dtilt has similar uselessness, as well. UAir's visual is a lie and the hit-box is far smaller, and it just isn't very strong, and DAir IS pretty much just useless meteor.
Some moves have very rare neat uses, but are otherwise worse to use than not. -_-
* Her specials are pretty disadvantageous to Zelda to use. Like, seriously 'nuff said. Pretty much don't use Nayru's or Din's, or Farore's outside of long recovery/Ledge stalling. Transform is, well.... Sheik. So not Zelda...
Basically, all of her is flawed. She makes a killing on FAir/BAir and Dsmash though. XD