Nice, but the loading time?

Simply put, I like the game. The idea is nice and the levels are certainly challenging.
Two negative points, though: The shortage of levels (but I understand that they require work), and the fact that it takes ages to load. I don't know why, but if it was because of the amount of data downloaded, then I don't get it, why.

Ruined by the sample

I very much agree with you - I wouldn't even recognize that as a cello o_o Seriously, it totally pretty much ruins the song. Otherwise the song is beautiful and soft and I like it!

Free samples are quite easy to find, though, just search for something like "free audio samples", find a nice site and be sure to check the license.

Groovy

This sounds very good for a WIP. I can't give a lot of constructive criticism, but if I was you, I'd turn up the piano a notch. It sometimes gets buried beneath the other stuff.
I'll have to check it out when it's completed, it's very promising.

Wow

From the very beginning, the tone of the strings is something that draws your attention to the song. Then the flute begins and the song turns out to be bliss, pure and simple. While the song begins beautifully and calmly, it turns out to be something very and truly epic. I just plainly love it.

As an interesting note, "glorious" was the first word that came to my mind when I heard the song. And this was before I knew the name of the song.