It's very difficult to make serious progress in terms of score, and the obstacles arriving from the top of the screen rather than right (as if you were flying forward) feels a bit odd. The game isn't spectacular but It does offer some light entertainment for a limited amount of time.

With HW acceleration off there is no challenge, with HW acc. on the game is barely playable.

How about a learning curve?

Pretty unique! I love a good challenge. Best I could do was only 10. ;P