The wish-granting energy being exchanged for negative energy made the Dragon Balls less haxed, and this revelation gave the Z Fighters the incentive to not overuse them next time, resulting in more reliance on one's strength than external magic. Furthermore, the final villain being the physical manifestation of the darkness that overshadowed the light of the orbs was an interesting twist. Not to mention Black Smoke Shenron's trolling was entertaining and deviated away from the usual seriousness of a Shenron of his position. Other than that, it was nice to see Vegeta ascend to Super Saiyan 4 and be of more use than in previous GT arcs, and the debut of Super Saiyan 4 Gogeta was cool.