I haven't figured out what to do with the minecarts yet, how to push them through? So, I left without getting anything, feeling a bit disappointed before the Tear of Ashi.
I didn't like the frequent small reinforcements; it's better to have them less often but in larger numbers. However, there are plenty of such minor details that distract the player and slow them down. You need to think too cleverly to know where to lead the player across the entire map and why.
I haven't found the second witch dolmen yet, where part of the key is supposed to be.
But overall, it's very engaging; I spent a week playing for an hour or two each evening.