It’s obnoxious. It’s to the point where you have to clear the same mobs two or three times in a cave. Not to mention it makes solo exploration nigh impossible in many areas, even many low-level areas. Like someone else mentioned, it ruins any sense of progress or accomplishment. I get that ANet doesn’t want to have people camping an area waiting forever for respawns, but I’d gladly wait a couple minutes if I knew that what I’d kill would stay dead and that I’d have enough time to get out of dodge before they magically reappeared, mocking my suspension of disbelief.