To get a high score, make a long combo of tricks. In practice, this means getting nice entry every time you land to water and continuing to next jump quickly to get it into same combo.
Not very good design. Watering can is inferior to the potion and spraying the bees is a waste of time. Easily gamed by industrial-style potion-flower production.
Kli, the difficulty comes from trying to build a high tower. My first wacky attempt was higher than yours, even though the tower collapsed before I managed to lay all bricks.
Nice computerization of old Labyrinth. 4/5. Stopping/starting the ball with mouse during the game is a handy tool, although it is not mentioned in the instructions. Is it bug or by design?