I think they are fun, if designed properly, they motivate you to explore different aspects of the game, the ones you'd never try otherwise.
Whether they do reset them or not, it's the same to me, I just want to know, so it won't happen I'll be earning achievements and they'll reset it in few days...
I guess they won't be resetting them at all, since the game was released yesterday and they for sure don't want to piss off players.
