I really liked Team Rocket's part of the episode. I also like how Colress was so apathetic toward using the Pokemon and Team Plasma without caring what happens. It was cool to see Pignite and Charizard interact, but I wish that it was in different circumstances.
Ash wanting to find Reshiram (for the second time or even the first one) is a weak reason to travel through Unova again since it should be possible to significantly shorten the journey by taking a boat to the closest area to the ruins.
Looking back, the Genosect reference in this episode was reminiscent of how Mewtwo got a few cameos in Kanto as foreshadowing for the first movie, except that the Genosect cameo here felt much less exciting to me.