The couple points I can offer for advice are as follows:
(This has already been touched upon) but I think the colors are too "muted/pasteled". Try sprucing it up with some tighter and brighter colors.
The other is with regard to spacing and text placement. The main section to the left is a little wide to be solely for content. Depending on what you plan on having for content (long articles etc) you might be better served to break it up into two sections, an action bar for the active page and one for the main content.
There is a general rule of thumb to on screen type, loosely it's that the human eye focuses better when it has as short of a distance as possible to travel when reading from left to right (and im sure the same can be said for right to left), making the main content narrower makes it more comfortable for your readers, and that should be your main priority.