This song is obviously loved by a lot of people, including me. It reminds others what it's like to be in love and sort of with you being afraid the person that you love doesn't love you back. But the song makes you feel good, happy, and sad, all at the same time.
Also, it's a really hard song to learn, and that's one of the things that makes it good to improve your oral skill.
Anyway, I'm yours is one of my most favorite songs ever!