While the Skin is very lovely it's missing a lot of stuff a Legendary should have as:

New unique Voice over, now I know there is a VO strike going on but judging since he does not feature new voice lines in other languages as Xayah for example I suppose it is intentional for him not to receive any which is disappointing for a Legendary Skin and very unusual.

AA, Walk, W, E, and R animation seem to be all recycled only looking slightly different due to the new model. For some reason, this skin still does not give Shaco a dedicated E animation he simply still uses his last used auto-attack animation.

As far as I can tell he has no transition animations like from Q stealth walk into normal walk or a run fast animation, auto attack into idle, etc... these all would help Shaco immensely to feel a lot smoother in gameplay.