What do you think about this portrait?

[KmH]

It had to be square format.

It is fully 2 stops under exposed based on checking the exposure using Ps CC Camera Raw.
I added +2 EV to get the facial highlights to 238 in the red channel. Note: 235 to 240 in the Red channel is an editing exposure standard for Caucasian skin highlights.
After adding the 2 EV her white shirt is R-247, G-249, B-254 - no clipping (blown out) but the Blue channel is close.

By using Camera Raw's RGB channel numbers you can check exposure, and your display calibration.

I then made the following Camera Raw adjustments: Clarity +40, Vibrance -10, Tone Curve - Medium Contrast. Sharpen - Amount +50, Radius 1.0, Detail 25, Masking 0.
Using PS CC and the Healing Brush tool I removed some skin blemishes on her left cheek and touched up the bags under her eyes.

I would have had her a bit more to camera left, and as mentioned further from the background to aid selective focus.

 

[paulvgmip]

Agreed on the underexposed, next time I would use a fill flash our a reflector.