What a "cute" game :)
From a pure gameplay loop perspective, the game is very fun. I appreciate that I could play it with only the mouse.
On my first run I made over 900 points, without finding any powerups or catching anything other then sheep. I have no idea if that's good or bad, as the highscores were pretty low. On the second run, I got 970 with finding a single powerup up (the sprint one) and catching 2 rabbits. I also wondered to the left, it was almost empty and wasted some of my time.
Basically, I don't see why I would try a third time, as I have no context if my performance was good or bad, or any sense of progress. Perhaps some of the animals or powerups would only appear after achieving some score, or some other unlock system. Anything that would motivate me to actually run again, see if I can do better and be curious how the next unlock/achievement will alter the game.
I will be playing more though, to get a better sense of the balance etc. that you mentioned in the post.