Howling Fjord drove me nuts trying to get into and out of the Alliance port, where those vrykul are constantly spawning around the gates.
Borean Tundra I felt was a victim of what they're trying to fix by removing the need to return to quest-givers on chains. The storylines are there, but unless you know them in advance I found myself doing them in a very fragmented manner.
If you go up to Coldarra and do all the quests there, you get your first glympse of an Aspect - in this case Malygos, under attack by red drakes.