Rendering in game engines

This something I'm just scouting as a friend showed me the render quality of game engines. All the issues with Maya and Mental Ray, yet to get my head round V-ray, Renderman or Arnold, everyone's preaching one or the other, and now Unreal Engine 4 is thrown in my face. The whole idea of rendering in real time sounds awesome, a little research and there seems to be a whole following of this so called Machinima with web groups and film festivals.

Little history rant: the alleged first was "Diary of a Camper" in 1996. Essentially a minute and a half shot of a game, Quake, with something of a narrative used for promoting it on the internet. Some folk argue there were earlier ones. It wasn't great, of course fans of games and game art hold nostalgic value to it. A tonne others followed, naturally following the expanding gamer sphere. In 2013, Lucasfilms started boasting game engines "will take the post out of post-production". This was while working on the soon-to-be-binned Star Wars 1313, although the live mocapping looked incredible. In the past game art looked so cheap, geometric. We film artists always bagged those game guys.

What blew me away was Unreal Engine 4:

The textures, the reflections, particle effects look incredible. The landscape shots in this clip were phenomenal. The only thing I really haven't been able to check out is how good it's hair and fur are. I saw a few demos on youtube and they looked lame.

Now this too, CryEngine:

Like Unreal, it seems pretty awesome. The atmospheric effects were cool. Again, I wish could find some good hair and fur shots. The only animal they show is a lizard... feels like a tactic. The water, especially the shot towards the end was incredible.