I love the new series. One of the biggest issues though that fans have that keep seeing in every discussion of Korea though is that the creators wanted to tell a new story and explore their world in a different way, but lots of the fans wanted more of the same style of story. But really with the exception of Zuko's mom, their story was done. Any other story beyond that one point would have to be smaller scale. Where do you go with those characters after defeating world conquering mad man that won't be a smaller scope? The outcry then would have been, they're just doing the same thing over again, why cant they come up with something new :-)
And the art style is very different, but it really does fit better with the type of story they're trying to tell then the style from the original series. I like it's but eh, that's just my opinion, I can see why some might not take to it.
As far as the story goes, it does start slow. Lots of exposition and showing how the world changed/advanced, and being introduced to all the new characters. That's the first 3 or 4 episodes right there even before they start alluding to the chi blockers. It does feel a bit rushed in parts and that they were going to try and do more with the love triangle(or love square? ) but they had to wrap it up because they weren't sure they had a second season. If they weren't picked up again, where they left off would be a fine place to leave the series. Compare that to the first series, they knew they had 3 seasons, the was /planned / around that. That makes it so much easier to make things flow that much smoother plot wise.
When Korra aired I was only able to catch episodes here or there ( or the same episode 3 times oddly enough) I didn't really get into it. It fell into the "that's neat but I'm not going to actively look for it" category. But I saw it on sale at Wal-mart and watched it as a whole, and the series really grows on you when you can see it in its entirety... and in order.