Last time I listened to NPR they were interviewing an Indian American woman who was talking about how it's not white peoples responsibility to take in millions and millions of Muslim migrants when their own people won't take them in and should. They would not let her get a word in by constantly interrupting her and all but accused her of being Islamophobic.
A lot of our perspective on the slant we perceive in news is going to depend on what we're used to. If you are used to a steady diet of Fox News, and similar reporting from far right news sources, I think NPR would sound quite leftist.
NPR isn't perfectly unbiased (it's not possible to be without bias), but they are very strong on their journalistic standards, which is the best that can be hoped for. It's good to remember that there is NO center from which to speak, except as an abstract concept.
Can you name a news organization, ChirpingGirl, which is less biased than NPR? Seriously, name it if you think it exists, and I'll consider it honestly and with an open mind.