I got this game and beat it tonight. Overall, it's a pretty good game, lots of fun. It wasn't much of a challenge however. The final battle is pretty interesting.

Anyway, good game overall, with lots of levels. I didn't bother to play through all of them as I usually beat a game first then go back and do that, so I still have replay value.

I do think it's a neat touch how the screens switch places when you warp underground.