I don't mind dappled backgrounds as long as it's not on the subject and as long as there is enough light on the person's face. I think it's totally fine here.
Is this an in camera crop? I'm wishing that it was either more of a close up or even pulled back further to include the rest of her arms and hands. It's cropped a little to close to her elbows for me. Focus looks great and I really like her expression.
The speckled light doesn't bother me except for the part right near her head and the upper right corner of the photo- my eye just wants to go up to that. Can you burn just that little bit out? The rest I like!