I think Destiny lacks a lot of polish. The enemies are kind of dull really. It's important to have enemies that you feel are worthy foes. They nailed it in Halo with the Elites, Grunts, Jackals, Hunters etc... but in Destiny I don't know they just felt generic as hell with no purpose.
I feel like the powers were more useful again't the other players than agains't the enemies, the enemies just needed better weaponry. I know I only play the beta but judging by some people's reactions it's not much better. So I don't plan on buying that game at all.
I had a problem with the AI as well. I think I have come to the understanding however that everything can't be as great as halo but It is really hard not to compare it to halo since it is Bungie.