If you don't grasp or miss the training on Level 2 (to click on your little blob to turn it to water), as you can just put it on the right hand side to let it get the key and tumble down the side, then by the next level you get stuck. Modifying Level 2 to force you to only be able to complete the level by clicking on the blob will ensure the user has mastered the technique and then doesn't get stuck later on.
The clicking on the block destruction could be made to feel more responsive, I have to wait for the completion of the previous block destruction (when click on the same split block) before I can continue which just feels slow.
Overall, not to bad but I would definitely recommend focusing some more time on the controls before your final release to get it to feel more refined experience.