I like it, very positive and childish in a way but generaly a nice experience. You repeat the piano drone "motif" alot in m. 59 - 122, and it is not interesting for that long. In these part the flute seems to get repetitive too. It may cause listener may feel bored in these parts. My advice must be that you should try to give your piece a little more time, and try to make this part more exciting.
I generaly like your move to Ab in the main theme, but you return immediately to the tonic, why not explore the key more by maybe "musically" suggesting that a modulation has taken place? I know you claim the title of traditionalist, but this should'nt affect the creative process, just write and forget about a specific style or tradition it gives more freedom in the writing process. If your use of simple harmony is because of lack of skill, then I suggest that you explore that area.
I like your composition, but it needs some work to keep me from getting a bit bored sometimes.