I would say this is more Ambient than Classical. But really genre placement isn't a big deal, and I'm sure it could go into either. I like the slow build up of intstruments and how they layer upon one another. However this type of song progression can feel a little repetitive and slow moving. Your piece certainly does move from it's start to a different place for it's end, but it is a little cliche and jolly for my liking. The end melodies are a little to simplistic and i think a little chromaticism may have been nice.
Still it's well mixed and the instruments all sound great, and my distaste for happy music is purely personal. Keep it up!