Aurelion Sol doesn't look well designed.
First of all, he is a ranged champion with a passive that seems to reward getting in the enemies' face. He even has ranged auto attacks, and is described as a midrange mage, but without his w his passive is melee (essentially, his W is a seperate move and he really has no passive, since melee champs will either delete him a second or be too tanky for a mage to deal with at short range)? It's also very slow moving hits instead of DoT, so the damage looks to be very inconsistent. Apparently, this is his main source of damage too, which i don't really get since he is meant to be a midrange champion? Other than clearing jungle, this passive looks unsuited to the rest of the kit.
Then his W, which being at a set range, requires a lot of intense mechanics and toggling on and off in order to deal consistent damage, where riot claims most of his damage will come from. Whilst you are kiting, both his other damaging ablilities are skill shots, q specifically having a slow missile speed AND needing the player to choose when to detonate it and if to follow the projectile (which doesnt make sense since a mage should be staying at range) and R probably on a long cooldown. Unless W damage becomes insane, i don't see how he will have a big impact in terms of damage, and if it does, lets think about this ability in combination with Rylais. The range on W combined with Rylais will make this champion seemingly unkitable and dealing large amounts of unavoidable damage to all champions spare those with a blink.
Take in Rylais and you have a champion VERY similar to Anivia. A mid range, zoning mage who has the same Q and good cc, but since his W is toggleable, its arguable he will also be building ROA/Tear.
Of course, what he has that Anivia doesnt is more movement speed and an escape/engage, which is one of Anivia's main weaknesses. It seems like the damage on his passive will ultimately decide whether he is vastly under or over powered, as riot describes that is what his kit revolves around. However, given the thin hit box of the passive and W, multiple skillshots and needing PRECISE movement of the champion on his W, Q and Passive, coupled with his E not allowing sharp turns without a price, this champion looks like he will have an extremely high skill cap and fall to the bottom of the ladder after time.
PS - These are personal opinions, and I'm just saying what I think. I am not good at the game, so what do I know? I just wanted to see everyone's opinions on the new champion. The visuals at least look stunning <3