Perhaps a bit too casual for what most consider a "portrait" - more of a candid? I think having the cup hide half her face does tend to detract as well.
This is a really interesting photograph. I like the fact the model looks more interested in what is going on around her than in the photographer. She looks like an active person with a few stories to tell.
I don't know if I'm being silly or you are, I love this in spite of myself. I think the really big issue with me is the crop. Great colors and personal details. 8