The cello here isn't a good lead. It's buzzy and there's too much reverb on it.
You need to pay a lot more attention to velocities when you're sequencing. You have a lot of successive notes that are the same velocity in the harp, piano, and cello lines. As a rule of thumb, velocities from note to note should always at least slightly differ from one another. Think about a person playing a piano: when he plays, he's not going to press every key of the piano with the exact same amount of force; depending on how his hand is positioned, the note he played previously, and other factors, the next note will be quieter or louder. This goes the same for other instruments as well.
When you produce music on a computer with your mouse, you have to remember that even though you're "writing" the notes into the computer, you're still a performer, and you have to perform your music.