It doesn't feel finished. The shading could use some work, especially in the leaves. The leaves feel flat, and it doesn't seem like you had a direction for the leaves to come from and go to. The little bushel of leaves in the front-left feels odd.

Overall decent effort, but again it could still use some more work. Try to apply a few of the linked tutorials to the tree, or another tree attempt.

Some random tree tutorials I found via a google search. They look pretty good.
http://fc03.deviantart.net/fs49/f/20...by_D_e_n_a.png
http://www.vbgore.com/images/hosted/mith4.png
http://0.tqn.com/d/graphicssoft/1/0/...k23-14tree.gif