The SMS thing works ok - I can receive but not send. Phone calls have never worked for me which is a shame as this was one of the features I was really looking forward to. Mail is pretty unstable. Other than that, I've been enjoying using Yosemite from Preview 1.

It's flaky at best. Sometimes calls show up, sometimes they show up a few seconds later. Often times, they don't disappear when you accept it on your phone.

Definitely not as polished as in their demo yet.

Worked for me in beta 3, but they removed it in beta 4. Also, sending SMS from Mac doesn't work anymore.

It worked at beta 3 for me :)

By treating them as they are - completely different things. The phone call stuff just makes the Mac a Bluetooth headset and routes the audio accordingly. After whatever wizardry they use to connect the phone to the computer is done, it should be easy.