As well as being quite grey, the white main area really blends into the background, leaving it difficult to distinguish between the two. You need more contrast on your colours, and on your text.

I appreciate the way you have chosen different colours in your text to add something to the design but this needs to be continued throughout the layout.

If you keep going the way its going i can see it ending up very flat, so more colour, more contrast. Also..make the nav text a little bigger...it'll be easier on the eyes.