I'm going to start this review by saying that I enjoyed the season. The characters were nice, even Mako. It felt like A:TLA, which was a pleasant surprise. However, I was also disappointed. A span of 12 or so episodes isn't enough room for a major plot arc.
So instead of saving content for next season, there was so much going on some of it couldn't even be answered well, or at all. The love triangle, Hiroshi and his family, Amon and the Equalists, bloodbending, it just could have been answered so much better (Most of this stuff starts and ends between episode 5 and 12). However, their is something old fans will certainly appreciate.
1. Fight scenes feel like fight scenes. You'll be amazed by the stuff happening in the last 4 episodes.
2. Good voice acting and characters. Amon is even voiced by Steve Blum, the voice of many famous characters.
3. The animation is great. It looks like an anime with Western effects.
4. Nostalgia, need I say more?