I love bright, sunny outdoor crawlers like this.
There's a little visual inconsistency in the assets, and I would've loved to see a more cartoony skybox. Also, the frog's damage animation feels a bit more like it's jumping at me than taking damage. Flashing monsters white or red when they take damage and adding some sound effects (SFXR is a great, quick way to make sound when you don't have much time) might be more clear.
Overall, very pleasant look and feel, and the music fits well; I could see this doing really well on a mobile platform.