It's hard
This game is very good, but it's also very hard. I enjoy playing it, but the enjoyment ends at a point where it's impossible to go further.
I don't know, the rewards just aren't THAT good, and you can only carry a few of them too.
Too many kinds of enemies, are way too complex to slash, making the sword pointless.
Beating the small nest is possible AND fun. Beating the medium one is not something I'm going to achieve though. There's a point where there are, no matter what, too many critters on screen that can NOT be beaten by swinging them. This includes boulders, sharpies (1 second no spikes during which they're beatable for minutes long of rolling around with spikes is not fair), greys (possible to beat but not once there are manny critters), horrors, ...
I know there's a bigger sword if you can beat a queen. However, even after me playing this game for multiple hours, there are certain monster types that I have never even encountered, despite playing all game types even in hardcore mode! No fire things, no ice things and no queens seen so far and I have no idea when I will see those or what to do to get them. So how am I going to get that sword, that will be needed to enjoy the rest of the game, if the monsters needed for it don't even appear, and if probably to be able to beat a queen you'll in fact NEED that very sword?
So in conclusion, FUN (so high score from me), but too hard, at a certain point it's not possible to continue. The rewards should be better and it should be possible earlier already to somehow upgrade your sword.