I've been working under the assumption that there would come an update where mobs would be able to destroy blocks since I bought the game as that was one of the central ideas behind Notch's zombie siege mode. So the prospect of endermen breaking down my walls doesn't bother me so much so long as it's not that common.
As for their new teleporting ability, I don't like the sound of it. I spend many nights in the game on top of my tower looking out over my domain, but if an enderman spawns in front of me while I'm up there I'm going to have to stare at him all night otherwise he'll magically teleport behind me, 30m in the air? The only way I can see that gimmick working is if they only spawn in caves.