I like that little echo the piano has as well, gives a feel of being in a hallway somewhere and just enjoying the music as well. As for it being ambient, I would have to disagree and say it is classical instead as this is piano only. Ambient is more of a genre where you let the sounds paint the scene and tone for a place.
Very nice piano playing however, the echo effect is a nice thing worked with on this piece too. Not too bad at all.
Overall, nice classical piano piece.