should i feel bad?

It's a comedy and Streep was being deliberately comical so no.you shouldn't feel bad. There was lots of laughter in the theater I was in.

That is the weird thing isn't it? It's so funny, I was laughing hysterically as well. But it's not really laughing AT her for the bad singing. It's unintentional brilliant comedy.

There is something endearing about it as well. Like "screw it I love singing" which kind of takes the sting out of it. It isn't really worse than what many people sing for Karaoke. The public humiliation is part of it but it's also lovely to see the courage to do it anyway. "People may say I can't sing," she once remarked to a friend, "but no one can ever say I didn't sing."

In a way she was a cripple (syphilis might have attacked her brain / ability to vocalize and the arsenic treatment might have caused nerve damage / hearing loss). So she might be actually convinced she hit a note or got the rythm right while the part of her brain that is responsible for this is playing tricks on her. So you should really feel very very bad at laughing at a cripple! You are a horrible person! :D

I think it was the unexpectedness of it. I had actually heard of this woman before, but I didn't know this was her story. As soon as she started singing, I knew :)

But the thing that was undoubtedly funny was the piano player's face :D

I did actually stop laughing at Florence's singing after a time out of respect for her 'condition.' Generally this movie is both funny and sensitive in equal measures.