Hmm, I misunderstood the subject line to mean "peeve" instead of "difficulty." Ah, well. I'll also say grapple for my biggest difficulty with the 3E rules. As far as biggest peeve/annoyance, at first I didn't like how they changed the rules to make it more difficult to interupt a spell in progress via an attack; now you have to ready an action ahead of time to do so, AND the caster still gets a concentration if you hit. In contrast, in 1E and 2E any damage would do the trick, and you could react after the spell was started if the spell's casting time was long enough. I'm getting more comfortable with the new way of doing things now, though.