Yes, there is room for improvement. I'm sorry, but I have to be truthful.
To start, well, it's about the start. I can't exactly pinpoint it, but there's a moment there that ruins the build-up. After hearing it, I shudder in the beginning because I know there's a point somewhere where it messes up and throws me off. I think it's around the 0:40 mark.
Secondly, halfway through the piece it sounds like a power struggle for the parts. I don't feel the cooperation anymore and everything goes into disaster in my ears.
If it helps, try and stop one part from playing and let the other parts of the music pick up where it left off. Then do it to another part and so forth so on to let the listener know where everything is coming from.
You see, I see music as a movie trailer of sorts. Forgive me if that sounds weird, but when there's a piece made into its fullest potential, I can set up a theme, characters, scenes, action, emotion, and all that. So far, I got couple scenes, but that's it.
You have taken a step in the right direction with switching what plays the melody though. I'll give you that. You just need to get a rising action, a climax, and a falling action well sorted out.
I'm sure you know Luigi's Mansion. Listen to it's music for awhile and you might get at least a hint of what I'm talking about if you don't understand me. And if you don't, don't worry. You're not the first one.