[niceshot]

it really depends on how you want to portray your subject. I think in this case,personally I would prefer a slightly unsaturated dramatic look.something like this :

Nah Mee nailed it

[Roypercy]

Nice pic. What was your shutter speed? I see your ISO was 1600 so I'm assuming there wasn't a lot of light to begin with, but if you could perhaps have slowed the shutter down a bit it might have made for some nicer contrast and more dynamic range. I'm missing the effect of the strong light from the open window.

[robgski]

I am pretty sure with some more practice I could probably do more formal portraits, but for some reason I really like the unplanned stuff.

I can understand that sentiment, when people are animated and informal they reveal more personality. Getting the model to interact a bit and relax, as opposed to sitting still for the camera is the way we see most people, dynamic , not static.
I think you got one of the most important features of a portrait correct ; the eyes. They are illuminated, and in focus, they catch attention and serve as the centerpiece. I didn't notice anything else until after I took in the detail in the eyes. There is fine detail in the hair, and the face is in focus and though the left side of the face is slightly shadowed, it's not bad. I don't find the backdrop distracting because the subject is well captured.