@Richard
A few years ago I'd have been in absolute agreement with what you just said due to the way games looked to me, but the abilities of that engine are truly incredible, you can go as deep as you like, you can even create your own shaders from scratch if it lacks something you want.  If you want a mirror in a mirror, you can have it no doubt.

Anyway, I'd hate to start pissing people off, I'm just pointing out what it is and what it can do, and as far as I can tell, there's nothing that can be done in a raytracer that cannot be done in realtime in that engine, some way or some how, and even if there was, someone will add it before too long.

I've found the "official" introduction which shows how easy it is to get to grips with, it's part of a set so if you let it run to the end it will automatically load the next video and the next etc, gradually you learn how easy it all is:

Click for Official Unreal Engine Introduction