I do not agree. A candid portrait is still a portrait.
Quick, yes, I think, because it needs a bit more space at the top for her vision line. But I like it overall. Strong background that does not get in the way and fairly nice comp. It does however look soft, as in not quite focused right. There is also no detail in her hair and the rest of the tones in her face are pretty greyish. The PP needs some work.
I agree with c.cloud, it is a good start and beside the other points cloud made I think the shadow on the shirt is distracting as well. To me it looks like you were using a 50mm f1.8 or f1.4 and with the appreture at wide open it can be difficult to get the whole face in focus being that close, at least that is a problem I have ran into.