I generally don't like musicals except for Enchanted, which I attribute to Disney kind of making fun of itself. However I've never seen a proper stage musical and as BTTF is one of my favourite films ever, I went to see the musical earlier this year.
I can't deny I was really entertained all the way through but I had no idea there was going to be about five minutes of "normalcy" before another song kicks in. I think there's around 14 songs in total.
Part of the magic is what is achieved on stage for sequences like the DeLorean driving around trying to get up to speeds of 88mph. I feel some of that would be lost in a transition to film because, in a way, that already exists.