The episode did a good job at setting up the issues for the rest of the series. I prefer that for once that the series is showing us the fallout and consequences of the last arc in detail. The inequality issue got solved in 6 month time skip by electing a non bender president. The human and spirits learning to live together was ignored in the last book and glossed over in the 3 year time skip for this book. This book the fallout is still going on. Zaheer's actions destabilized the Earth Kingdom and fixing it in a short amount of time would have been unlikely.
Kuvira is shaping up to be our main villain and was introduced in at the end of book 3, so we knew she would be a character in book 4 to get more focus. The prince is annoying that's his purpose. The conflict with the Earth Kingdom has is it wants to go back to monarchy or new order. The prince being annoying, entitled, and drama king highlights how ineffective he would be as a ruler and shows why people in the Earth Kingdom don't want another king or queen (after the Earth Queen's actions caused the one great nation to be on the brink of poverty and forced them to live under her iron fist) and why Kuvira who is unifying the kingdom back under one rule, providing people food, water, or protection for bandits and thieves etc, but is doing it through force and making them all join her or else, is gaining so much support. This also shows the consequences of the Avatar being unable to do her job. Bolin joined her means he believes they're doing good. Tenzin and Lin clearly believe Kuvira has been doing a good job at re-uniting the Earth Kingdom (and unaware of her methods or possible take over) which gives us conflict of Bolin being on the wrong side and possibly against Mako who is now the prince's bodyguard. Korra of course is in a bad place. She's defined herself as the Avatar her whole life and she was unable to do her job, but seemingly other people stepped in to fill her role, playing on a fear that the world doesn't need the Avatar anymore.
The episode introduced all of this because it sets up the plot for the arc and possibly the final chapter of the whole Avatar saga. The premiere was a setup episode, but I don't think it makes it a bad episode. I also don't think the episode introduced too many new characters that the story will suffer for it. Kuvira is our villain (seemingly) and we already now the conflict way faster than we did in book 3, which took several episodes before we even knew Zaheer's group's name or their purpose.