Korra is basically a real 16 year old girl, she makes mistakes, lashes out at people and is very naive. I personally like how real she is but yeah she could be a little nicer, she isnt an adult she may have to save the world but she is still only a teenager.
True, though I think the main downside according to many is that she should have already developed since last season. Now, it's a repeat in a different situation. That's why many hoped she's already moved on and understand the hardship, especially since she at one point lost all bending. I don't know, but that's how I see it from others.