I’m loving the story so far. I’m not usually the type to care that much about that end. But I am finding myself really wanting to read what is going on as I progress. Also the basic battle mechanics, I think are just fine. Nice balance between strategy and speed.
Chests, keys, inventory etc? Meh. Absolutely horrible and demoralizing out of the gate. But it does mellow out relatively well, eventually. As a player that stuck it out through the early bits, I’m kinda fine now there. But I do worry that in full release you will lose newbies left and right who won’t be as willing to “eat their spinach.” This issue could be more or less solved by toning down the drop rate of higher chests at lower levels.
Balance and progression? Woof! Some major issues here. Most of them have been talked up in other threads. I’ll try to articulate what I see as the biggest issue(s).
Enemy number one is that the hero leveling curve is way too gentle and the gear leveling curve is way too harsh. Its not bad to have heroes level faster than gear, because that is where your monetization seems to come in. So the issue is not the gap. Its the size of the gap, and the insurmountability of the gap. (stop and grind for shards? congrats you leveled 5 times and can raise your gear 1 notch… aka worse off 
) Solution? Tweak experience down and tweak shards up.
This is hands down the biggest issue I see here. Even looking at it as someone who believes in paying for games… there is no way to overcome this problem, currently, other than playing the meta. If I’m using the exact same strategy and almost the exact same spells on two different heroes? How bored am I going to be very soon?
I forgive all of this. Its early access and this is why we are here! I think the game has real promise and I hope you take this feedback in the spirit it was intended.