The game is 2.5d. Neither 2d or 3d. The demo looks really good. I hope i get to play it on pc one day.
I like their approach to making this game in that they tried to recreate the original but taking advantage of modern hardware. Watching the interview recently it is obvious the developers are fans of the game. For example, they even put the jet engines in there!
I also liked the background graphics. It's spot on. Very atmospheric. I only hope the music is on the same par as this.