I'd say we're seeing evidence that it's failed in Europe.
However, good people and bad people come in all races and Religions. I'm trying to purge all bigoted sentiments from my heart. I've known some very good Muslims. I will face Mecca with them, pray, listen, and study the Koran with them.
I think you need to be careful conflating multiculturalism with Islam. You can think that Islam can't integrate, and still think multiculturalism on the whole is a positive thing.