So I guess this is out now
Anyone actually excited? I rarely use Siri on my phone, so I can't see myself suddenly talking to my computer all the time. Things like auto unlock (if you have the watch) and Apple Pay for websites seem like niche, ho-hum features. Handoff has been nice, so I can see universal clipboard being a useful extension of that.
Otherwise, let's see ... uh, app tabs? OK. Something to do with Photos? It's a mess anyway. Something about Apple Music in iTunes? Meaning, just a better way for them to push that paid service?
I'm still using Yosemite on my primary Mac and have El Capitan on another one; by and large I find no difference between the two except El Cap actually *took away* features in some places (e.g. Disk Utility).
But hey, I've resisted just about every Mac OS update to one extent or another since Lion, so maybe I'm just a cranky old change-averse cynic.