I would say acoustic version of a song is often way better than its original one. Sometimes, it gives me clue whether the singer has good or bad quality. When they use minimal instrument, you can hear their voice clearly, and you can tell their mistakes easily :p
Great DJ by The Ting Tings is just one example. I knew this song from TV commercial 3 years ago. Back then, my first impression was just “Ok”. Today -yup in 2012-, when I was watching Sunao Ni Narunakute (one of J-dramas or dorama), I heard the song again. Its acoustic mode was played as back-sound in some scenes . I felt like “Wow, this song sounds different!”. I mean, with slower tempo, it produces different sensation. Plus, their voices blended perfectly, makes it more beautiful than the original one. Don’t you agree with me?