The "new" railfan mode is nothing special. It's basically a scenario with AI trains setup to pass by with you spawned in an invisible vehicle on an invisible track so it
seems like you are just watching. In actuality, because you are technically assigned to a locomotive, you have a limited area of space you can move from your spawn point. This was made for people who don't know how to setup a free roam scenario with AI trains (although you have free range of moving in free roam). Again, it's nothing new. It's simply a scenario with AI trains and you spawn into an invisible vehicle on an invisible track so it looks like you're standing.
The driver assist actually is a new feature. The only thing I can say against it is just how annoying it is when you're trying to get good out-of-cab views and it moves your camera back to the cab to show you what to do. I'd personally love to see this feature on Mike's FEF-3, since... well, you know.
