It looks quite bad. The yellow doesn't go too well with the white. There should be a better contrast between the white and the black/grey, whereby the white be brighter or the grey be darker. More focus should be applied to the circular design at the end of the arm with details etc, to make stand out. There should be lesser yellow at the sides (if you were aiming for a shiny look). However if what you wanted was a more circuitry or tech like feel, a brighter yellow will definitely improve it. So far, only the elbow sections look good.
Despite the text that I have typed above, it isn't bad for a first attempt. Hopefully you'll continue modding.