Wow, I just finished the prototype. I realise it was always intended for some form of public consumption from the outset, but that was one of the most polished prototypes I've ever played. Shockingly bug-free and very cohesive even at this stage.
I think my biggest complaint was a lack of enough indication between the different phases of the battle. I was keeping such a close eye on my meters that I rarely noticed when enemies had reached the stage in which they could attack, which meant that I usually missed the red flashing indicator for their target, flailed a lot with my block attempts and wasn't very successful at them.
Maybe some sound effect indicator when an enemy is going to attack would help? Like a sword-clash "ka-ching" kind of sound effect - something short and high-pitched so it stands out against the music and general other battle sound effects (i.e. the hit sounds, which are bassy and low). Dunno, that's just my initial thought, there's probably a better way.
Relatedly, because I was flailing a lot and button mashing to try and get attacks out, as I wasn't noticing when the enemy attack phases began, I ended up trying to attack when the game wanted me to block, which led to a few confusing (literal) moments.
For a prototype though, that's nitpicky stuff. The fact it works and flows so well at this stage is a hell of an achievement in itself. Definitely confident in my contribution after playing this.