What is the current status of Multi-Sign function in bitcoin network? Are they convenient enough for some real world transactions? Like an easy escrow that the two party can assign to a third party to finish a transaction?
This topic has gotten a lot of traction recently, with new implementations continually popping out.

For example, there's a really nice standalone HTML5 app with slick interface called Copay, developed by Bitpay. There's also an online service BitGo (haven't tried this one though).