I do love the foundation of this game, especially as it pays homage to PvZ and Toys VS Nightmares. I liked the art style, the aesthetic, and the mechanics involved. There is just a few problems present...
As others previously said, the wave spawns can be a bit atrocious in the early game, especially when you don't have enough to cover a lot of the lanes. Not only that, there is no way to know what your toys can do initally, since you're preoccupied in handling the music box.
The later enemy types can be a bit difficult to counter in the early game, due to the first issue present. The enemy with the music playing is not only deadly as it boosts the other enemies, but it is tanky as heck. The bicycle enemies can be a bit annoying to deal with if you don't have enough firepower to plow through the hordes of enemies in one lane, killing your setup immediately, which is a huge difficulty spike.
I did played both PvZ and PvZ2 Reflourished, so I have some knowledge on how to counter these issues. However, the way they spawn the zombies in those games is based on a set amount per each wave and some waves are pre-determined with what zombies to put. The random part in there is the lane positions. However, they also avoid heavily congesting multiple zombies of a single wave into one lane, so that it's doable.
That said, I kinda wish this game is expanded upon. Hopefully to see more in the future.