I'm not really a fan of the artwork or the artstyle, but that's subjective, and the ability to see the splash art was a detail that wasn't necessary but highly appreciated. However, the effects I do
love. They went into so much detail for the champions. Garen's animations are spinning swords, Thresh animations pull souls from defeated cards, Teemo's mushrooms explode, given how many champions there are this was probably tons of work and it looks wonderful. And like you said the voice overs are champions dependent and reference the lore, as should be expected from a game about a 10 year old IP.
I disagree about the complexity though. It's definitely a lot more involved than HS and that's the similarity with Yugi that I see. Fast spells being played from the hand and turns allowing actions and reactions from both players in every step is going to require you to become familiar with all possible cards from the regions of the opponent's deck and all situations you may be getting baited into because they may spring a card that would force you to change your turn halfway through. While in HS, at least until last I played, a player is in complete control of what occurs during their turn (barring the "do X at random" cards) and there's no way to answer it in real time outside of secrets, which leads to things feeling very telegraphed.
I think you are underestimating how many "you activated my trap card" situations this kind of gameplay lends itself to. And that makes it feel a lot more dynamic and fun than HS!
I dunno much about the monetization though so I'll just hope you are right.