B_T: sorry to bug you. I love the cover you designed. I know you didn't solicit for any comments/suggestions, so forgive me!
IMHO, the only thing I would tweak is the title "Mysterious Song"—it does not clearly stand out from the images. Possible solutions? I think that stroke (outside, black, a few pixels larger than currently shown) might do the trick. It would ruin the nice thin black line outline, though, but the alternatives (like a subtle semi-sharp shadow) may not fit the aesthetic style you were going for.
And/or...shrink the title put it off-center.
I'll stop with the unsolicited comments. I just wanted to give my 2 rubles of advice. Don't hate me! I love all your work