Well done on your first try with illustrator \o/ For my first time, I had to trace a picture of a car. It was horrible >.<
I love and simply adore simple design and concept but this one isn't doing it for me. I feel like it lacks direction and that bit of element that could turn it into something a little more special. Composition and color wise, it's okay even though I felt that it is pretty static.
Just a bit of suggestion you could try; add shadow effect to make the image of the characters to look like cut outs or change the background beige or white to give a stronger contrast. Or try adding different texture on the character than the background.