Just three words: WOW! Now I would wait for the Technical update and then implement lightning (cause then we have real illumination for RW) and it's absolutely perfect.
Just so it doesn't loop the same thing over and over again. It get a little irritating after a while. I hope as I drive the rain stops and starts randomly.
Currently there are 7 randomly choosen sound files it plays, I will add more as I develop before I release this.
So far today I'm concentrating on the actual weather itself. ie: Rain and Clouds.. It's amazing what can be done with the sky if you actually understand the weird way Railworks does weather. But, it's insanely configurable and powerful.