A word to those aiming to watch Legend of Korra now that it's on Netflix, but haven't gotten around to: Don't expect Avatar.
ATLA and LoK are similar in multiple ways, but have fundamental differences you can't change. Here are a list of differences you'll want to keep in mind:
Korra isn't Aang. Aang was a twelve year old raised to be a pacifist, Korra is a seventeen year old raised to be the Avatar. Aang said "I don't wanna be the Avatar", Korra said "Why won't you let me be the Avatar?" Don't expect another Aang.
The series wasn't planned. It was originally intended to be a mini-series, but then someone said "Make it a series", and they were never been certain if there was going to be another season or there wouldn't be until the end of season 4. As such, the seasons are more self-contained. You don't have the overarching plot of Avatar.
The tone isn't as cheerful. With the characters getting older, the conflicts have gotten less "generally acceptable for children", whatever the hell that means. You have fascists, not imperialists. You have a blatant parallel to a race war in the first season, if that didn't tip you off. The characters are also more serious, and that might not be your cup of tea.
The world has changed. The technology has advanced, and places have changed, peoples aren't the same. The rarity of certain bending styles has gone down, though they're not universal. The Southern Water Tribe is a thriving port town, not barely a village! The land might not have changed, but the map isn't the same.
That's what isn't the same. I don't want you to think that makes it inferior. In fact, I don’t think they could ever reach the heights of the original series. However, that doesn't mean it's worthless. There's a lot for it to offer, but I want you to discover those things for yourself.
Oh, and badly written romances are a trend, not a fluke. That's something that stayed the same.