Story:
This is still a demo, so I can't completely judge the story. However, from what I've played so far it's actually pretty intriguing if you take the time to read it. There's even some humor thrown in there!

Gameplay:
I have yet to find a bug in the game that might stop me from moving on or ruin the experience.

The controls worked perfect on my LG Optimus (can't speak for everyone else out there). I would recommend using the touchscreen controls rather than the trackball, just because it makes it easier to navigate. It is a cool extra feature that you can choose that control scheme though.

You really need to pay attention to the tutorials in the beginning if you want to figure out, first of all how to play, and second how to solve the later puzzles.

Challenge:
I'd say the game was about medium challenge through all the puzzles and the overall difficulty of the enemies.

Other Thoughts:
I can't wait for the game to be completely finished! So far the story has been pretty interesting, I'd love to see where the developer decides to take it.