King's Landing: Short and sweet. Cersei's reduced to drinking a lesser vintage. The work continues.
Winterfell: More uncertainty about where this plot is going. Sansa knows her brothers are somewhere. Ramsay venturing out with a crack squad. Roose allowing this to happen implies he's willing to let Ramsay die. As are we all.
Braavos: Beautiful scenery. Dorne looks and feels empty because they decided to film it in a historical landmark. Braavos is filmed in Croatia, where people live, thus making it feel so much more real. As far as the actual assassination plot, they might've made it very clear exactly how it's going to down, but that might just be setting up a reversal.
Mereen: Would've easily been the best part of the episode in an average week. Surprisingly emotional stuff from Jorah, as Tyrion breaks down his thought process. He loved Dany, but didn't trust her. Tyrion then does a classic reverse-sell, in which Dany has to prove to him that she's worthy of his counsel. And she already knows to not let him drink so much! The world gets smaller, the show gets better.
Hardhome: Of course, all the plans of the Boltons and Cersei's possible trial and Arya's training are completely small-minded and missing the bigger picture, which we got our clearest understanding of thus far. Men plan, the Night's King laughs. Kit Harington doing fine work in the tent, but very nearly gets upstaged by the actress playing Karsi the wildling captain, on the show for all of 20 minutes. The inevitability of the attack was dragged out for the exact right amount of time, and then the mist starts billowing down the mountain. So many great touches on the attack itself, starting with the abrupt silencing of the wildlings left outside the gate and continuing with the wight frantically clawing itself under the wall. That first shot of the White Walker horseman staring down into the valley is one of the best of the series. The White Walker duel with Jon and the Magnar was perfect, with Harington selling his fear and then his surprise, culminating in the only victory of the sequence with the Walker bursting into pieces, the effects much improved from when Sam killed his. More escalation with the wight children and the avalanche of wights pouring down the cliff, until there's nothing left but to run to the shore, swinging a log. The Night's King raising the dead could've been corny, but damn, that smug look and the silence of the scene completely sold it.
While not as technically impressive as the Wall battle and not as interesting on a character level as Blackwater, Hardhome was definitely the most visually impressive of the three big battle sequences. Absolute A of an episode. Good timing on the show's part to balance the worst episode they've ever done with one of their best.