I like achievements. I usually won't hunt for them but the little extra gratification is nice. On Nintendo games I'm not really missing them...

But on games I like and I "finished" (killed the final boss / beat the last level / ...), I most often can't get myself to play them anymore since I have no goal anymore. And this is at that point that I sometime choose to chase achievement to 100% a game (extending its lifetime).

I could also look online for what's hidden that I did not do... but the achievements are already tailored to my playthrough and may give hint "spoil free". Online guides both spoil the puzzles and the reward...