I recommend making the card animations snappier / quicker, and making a different animation for when you match than from when you turn over a card. The Animator feature in Unity would be useful for animating the UI (and cards too). But anyways nice work. Good luck on future projects.

The theme is new and interesting, and the graphic design is nice. I like the variety of powerups. I think it would benefit from recording best time, or highscores, even if they are local. It would be nice to have the powerups easier to distinguish from each other, possibly with different colors.

Some more ideas for ghosts would be
1. ghosts which shoot.. magic
2. ghosts which wrap around the screen
3. ghosts that grow/shrink on an oscillation
4. ghosts that follow you (or perhaps just a single ghost that follows you to prevent the player from being able to leave the character in the corner).

Great level design makes the simple concept really engaging, nice game.