Always shielded? It lasts 1.5 seconds out of 9-10 early game. It's the shortest shield in the game ...
I honestly never have problems against Riven top unless i'm playing Vlad, and even then you outscale her pretty quickly. I've had games where I die to her multiple times in the laning phase, then at 10-11 she just can't solo me anymore.
She's also very hard to play despite popular conceptions. She's also countered very hard by certain champs, like Tryndamere and Trundle who reduce her AD (thus reducing the damage [and shield] of all of her abilities).
Ranged AoE execute ... lol. You mean it does trash damage unless they're low?
-no sustain
-worst base hp regen in the game
-scales poorly compared to other melee tops
-no ranged abilities outside of the "ranged AOE execute"
-easy to counter
-has to snowball to remain relevant
-falls off very hard since she's a melee AD champ that doesn't build crit and is rather squishy, especially when you consider the fact that no one builds defensive items on her (check probuilds).