I think this is a classic example of the background fighting with your subject. If she was out a little more, with the background a little more out of focus. Also, the harsh lighting doesn't help much, although you've controlled it well.
I really like the vivid colors and the composition of your image. The only thing I'd like to see is the left side of the image cropped in against the wall to eliminate the street. Other than that, great shot!
Love those reds and pinks that are very vibrant in this candid photo of this (Bolivian or Peruvian?) woman. And to make the composition interesting is the juxtaposition of two 'cultures': one is the south american culture with the woman dressed in the native costume and the other is the red brick wall advertising a bit of americana, Coca-Cola. I have two critiques on improving this photo. The first is to crop out the bit of street that you see on the left hand side of the composition. It adds nothing to the overall composition - in fact it distracts attention away from the main focus. The second is to see if you could get your model/subject to pose a tad more relaxed. It appears here that she is a little too nervous to pose for the camera; she is a bit too wooden. Hmmm, it maybe that the culture might still hold to the ideas that by taking a picture you are capturing there soul which would explain her unease.