The main advantages are it changing the lighting completely in the game, taking the (in my experience) washed-out default lighting and giving units realistic reflections, along with making night-time actually dark, meaning you're like a real-life driver whose lights don't really light up much of your surroundings and oyu're left to rely on route knowledge (or the HUD

). Dull days become more moody too, and
This is a screenshot on the Wherry Lines on a sunny day w/o RWE:
View attachment 94232
Then the same scenario with RWE:
View attachment 94231
In my opinion, the first one is dull, whereas the second is a) more aesthetically pleasing and b) more realistic lighting.
I wouldn't say it's at TSW levels as I've always felt TSW is far too blinding.