The idea is pretty old (well that's true for most games by now) nothing inovating here but executed pretty solid.
The choice of music was good too.
The graphic style is a little inconsistent I think.Like the screen where it does tell you the controls which you see as far as I could see only once (make a menupoint with instructions maybe (most people dont read it anyway though)) compared to the gamegraphics itself.
The station on the mainscreen looked a little ill fitted too.
Overall its as good as the portal average.