I am a massive Avatar fan but I knew I couldn't go into this expecting it to be the same as the original show. As its own thing, it is stunning to look at, and aside from some bad script writing and some meh acting (mainly from Katara), it is an alight show. Everyone I know who watched this without seeing the original enjoyed it.
However, it is nowhere near as good if we compare it to the original show. They have skipped over lots of character development and plot lines (as to be expected as there are only 8 episodes). I think the casting was good but they did Katara wrong. They made her blander than brown bread with hardly any lines. Also, she became a master waterbender overnight before she even made it to the Northern Water Tribe. In the next season, I hope they make sure they make her personality more than looking sad and philosophical.
All in all, it is good and I do hope there will be another season (knowing netflix they will make another one and then cancel it for its third season hehe).