Hmm, I can think of a few points here:
1. I dont have any trouble generally with the "homing" projectiles, or projectiles that are also enemies.... sorta same thing in this game.... but I'd rather they be a bit more creative than the fire shots are. Something like the attacks from the Nightmare Octopus; THOSE are interesting. The thing first of all doesnt sit there and spam 30 of them in 2 seconds, and when it DOES fire a couple, you have to be careful about where you pop them because they'll throw all of those "actual" projectiles everywhere. That's more interesting than just "thing that chases you".
2. Bats..... I dunno why players have such trouble with them? The cure for bats: the whip spells. Seriously. Bats have almost no health..... just smack the blasted things.
3. Worms. Ok, THESE are annoying. Too much health for something that JUST chases you (and is as common as these guys are).
4. GAAAAARGH RAPTORS, these guys, not the bats, are the "goddamn bats!" of the game for me. Omigod they're just so...... arrrrrrrgh. Particularly when they just suddenly FALL on me in a building. One moment, it's like, hum-de-dum, just walking along, pickin up stuff, ooh there's an item here, and then HOLYCRAP DINOSAUR ON YOUR HEAD. Though I'll say these guys got a good bit less irritating with the new bear traps; REALLY liking those.
5. Eagles. They're not as annoying as the raptors for one reason...... they're HARDLY THERE. Each eagle, you'll see it for like all of 1 second, and then it's just gone, off to another part of the map. They just seem like they could do with a revamp, really.