I absolutely love the base game and I'm happy to support the devs with my purchase of the dlc. Unfortunately I can't really recommend it to others unless they also just want to suport the devs and get a bit more Cassette Beasts in return.
Pros:
New monsters are cool, and I'm glad the content was approximately level 40. I was level 45 and needed to grind some before I did the endgame content in the base game so that worked well for me
Cons:
You're paying for 2-3 hours of content, and that content unfortunately isn't as good as the rest of the game. It feels a bit cheap with the bosses looking the same and with there being no vocals in the music. I know it's made by a 2 man team but I don't think it'll be worth the money unless it goes on sale for $3 or so
The reason I decided to write a negative review though was because it was also buggy. I fell into a hole in the witch house, was stuck there, and needed to restart the game to get out. It might've been intended to double jump out of the hole, but I didn't have that unlocked yet. The long rotating platforms in Funworld were also really buggy, at one point I got stuck at the end of one and my character kept spawning and dropping, spawning and dropping until I waited for a full rotation of the thing, but then I failed the jump multiple times so I was stuck there for minutes in total. I'm not even photosensitive and I started to feel a bit bad watching my character blink back and forth while I was stuck.
If it wasn't for the bugs I don't think this dlc was so bad to deserve a negative review, so I'll delete this review if I see fixes in future patch notes