I tend to look askance at 'automatic' achievements unless they are at seriously major points in the game.
Achievement for beating the final boss - Fine.
Achievement for defeating your first enemy - Are you kidding me?
By automatic, I mean things you can't play the game without encountering. I more enjoy achievements when they're optional, little flags that help me feel like my playthrough was different from other people's playthroughs and the game recognises my skills (or insanity, as the case may be.) "I finished Level 1" is not a meaningful achievement in my book.
As a developer generic achievements (if public or reported to a network) can be handy so that you can track how much of the game your players are regularly encountering and completing, but that can annoy them.