Year-old leak spookily accurate so far. http://www.bit-tech.net/news/gaming/2015/06/04/fallout-4-trailer/1
If the trailer is any indication then the lighting seems to have improved, but it appears we're still on the jerky old Creation engine. I expect to see your character's ass glitching through their post apocalyptic garb while shooting anything from more than 50 metres away remains an impossibility. I'm excited from a gameplay perspective, (pumped many hours into each of the FO franchise) but if they're still supporting PS3 and XB360 I'm not expecting many advancements on the visual front.
I find the trailer rather meh to be honest, also Witcher 3 has broken the concept of a good RPG for me, I'm not sure Bethedsa can step up to that level.