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!
Thanks man for your complete review, i appreciate :)