I've tried using it a few months ago. It's quite hard actually. The docs were poor, understanding the concepts was not easy and in a lot of places it abuses the Scala syntax:

LiftRules.rewrite.append { case RewriteRequest(ParsePath(List("shopInfo", "view", id), _, _, _), _, _) => RewriteResponse("shopInfo" :: "view" :: Nil, Map("id" -> id))

My opinion is that I don't like. At all! There are better and simpler ways to do things, even the real-time chats they brag about (socket.io, anyone?).