I use a Mac Mini, rMBP, retina iPad Mini, and iPhone 6S. I've never had any trouble with iCloud syncing personally, though I haven't used it for a ton of stuff

I use a Mac Mini, rMBP, retina iPad Mini, and iPhone 6S. I've never had any trouble with iCloud syncing personally, though I haven't used it for a ton of stuff. Photos is definitely the biggest use I've ever had for iCloud and it works flawlessly from day one for me.