So after having experienced the in game system I can say that I think it could be changed. I find that having separate achievements for each character gets rather tedious. Having to continually do the same ones over and over for each character is very time consuming.
I also find it to be a bit character breaking when I have to do things my characters shouldn't care about just to get the achievements. As an example, a fighter that would care nothing about making potions or enchanting, only his heavy armor and weapons.
It would be much better if there was one global set of achievements that you could complete with any character. That way it would stay more in lore and be less game breaking.
You search and search for something, never realizing it is within and always has been. You can not find it, you can not understand it, you simply accept, and believe, and it will grow. - Heretic's Faith, Randall N. Bills