According to many popular sites it is being reported that Apple Music has already reached 10 million subscribers ( Appleinsider ). This is of course an artificial number as none of those customers have yet to pay a penny for the service as it is free for the first three months of use.
The question I guess then is how many people will pay to use it beyond the trial period. My own experience so far is that I will continue to use it as I am finding the new music recommendations far superior to Spotify and the fact that the whole family can use it at the same time ( for a small increase in cost ) just seals the deal.