I've seen this being commented on a lot but I haven't seen a thread dedicated to it yet.
I am referring to the enemy AI, or rather the relative lack of it.
Enemies in this game generally
- Wander left and/or right, possibly chasing you or shooting at you if they notice you
- Wander all around if they can fly, possibly chasing or kiting you if they notice you
This gets boring, very fast.
Now for enemies you expect to be brain dead, like bats and those frost ball things, sure you can expect that.
But when the vast majority of enemies in this game feature this behavior, and the game was not designed from the ground up around that, this is not a good thing. (A game that was designed around that, for example, the original Super Mario Bros. on the NES, where it works in part because it was built for it)
Now there are enemies that avoid this, like the homing projectile enemies like faries (even if the homing behaviour itself could use some work; I am in support of giving "homers" a turning radius to make them feel more natural), some of the odd stuff like octopi, and even the fiendishly clever ones like the Utaraptors. However, these are far too few and in between, especially in the most common areas.
While I'm not advocating that every enemy be as smart or clever as the Utaraptors, it would be nice to see if some of the enemy types you would expect to see some level of intelligence from show some more variety in behavior, like skelebots.
This is especially true for bosses, which you expect to be a bit "smarter than the average esper". And even more especially true for lieutenants and overlords. These are after all the ones oppressing the land. The lieutenants had to be reasonably intelligent to win the favor of the overlords, and the overlord him/her/itself had to be pretty darn smart to pull his "reign of terror" off. Then why, in many cases, do they just act like dumb minions, with only slight buffs in behavior (larger detection radius, more shots, but nothing major)?