Thanks for reacting to this beautiful song. Gotye is a great sound designer. He uses everything, even a fence, to make beautiful music. Please check out more. He fimed a "making of" where you can watch him recording songs. Very interesting. Check out the music videos. They all are peaces of art.
That 'xylophone' sound might be a wurlitzer electric piano. That's the first name I thought of, & this is the first YT video I found. They sound similar to me. ru-vid.com/video/%D0%B2%D0%B8%D0%B4%D0%B5%D0%BE-nR1ltn3bPT4.html
'Somebody that I used to know' was covered by a Canadian group, Walk Off The World. The only way to 'hear' this is to watch the official video as all 5 members of the band play one guitar and three of them sing different parts. Extremely good cover. Try them next to each other. Gotye video is also good. This is very good too. Cheers Syed✌