So many complaints. My wife and I must have been lucky. Little problems for us.
My only request is to have the power to 'force' upload songs, so that they don't get replaced in the cloud with iTunes Store tracks. This has affected a handful of alternative recordings, such as rarities and bootlegs.
The tracks stay as they are on my Mac (as long as I keep the files there), but on my iPhone some are replaced after being 'matched.'