Achievements were novel to me during my 360 and early Steam days, but I can't say I really care about them anymore. When I really like a game I start digging its secrets out of pure curiosity, and in other cases I do self-imposed challenges.
My first contact with achievements of sorts was Super Mario Bros. Deluxe for the gbc. I was absolutely fascinated with unlocking things in that game. But nowadays I just prefer the plain NES version.
I really liked achievements in Spore though, and if a sequel ever released, I'd hype over them all over again.