I think Ke$ha kind of ruined this song for me by default. Blame modern radio, but I can't hear "You build me up, you break me down," without immediately thinking, "my heart it pounds, yeah you got me..."
I also think the song's vocal melodies are a bit too predictable/generic at times. "Obssession at all cost... you'll be the death of me... broken and torn apart... why can't you let me be." Compare with Seether's 'Because of Me': "Do you believe in love... like I believe in pain... nobody died for you... somebody pray for me." It's not identical, but Because of Me immediately jumped into my head when listening to that part of BMU,BMD.
Overall, I do enjoy the song, don't get me wrong. I think it's a cool song. It's just a bit generic to me. And while generic doesn't mean 'bad', it does mean it's less likely to be a favorite of mine.