this is obviously better with sound but, it's still good.
I watched it with sound.
The lip syncing is okay, but sometimes the mouth seems slightly off, like, the word/s doesn't go with the mouth, but that could just be my computer lagging like always, so I can't really say much about that XD
The quality of the drawings is good, and the way you timed things is perfect... I really like it!
The little heart beating bit is also pretty amazing...
Overall, I give this a 4/5 since it's a pretty basic animation, and it's not the whole song- yet it's better than most things I've seen...
Keep up the good work! <3