I don't find NPR to be very partisan. Their newscasts are actually some of the most non-partisan broadcasts I've heard. They just tell the story without opinions.
Generally half-way agree with you. They have a certain "enlightened" approach to the news which correlates to a liberal perspective. But the depth of their coverage usually makes up for it.
However since the conventions they have been in full-tilt pro-Obama mode. The morning after the debates was the worst. No mention of Romney dominating, instead it was a story about how Romney's numbers were bad and some random voter complaining how Romney hates women because he is against abortion.
This morning there was some grudging acknowledgment of Romney's win, but quickly followed by the jobs report.
They were always in Obama's camp; the shot at Big (government) Bird just put them in all-out battle stations mode.