It's not solely about visuals. I'd argue that physics and world interaction play a bigger role at this stage and will help improve immersion greatly.
The Battlefield 3 PC vs current gen consoles is actually a good comparison. The scale is one thing but it's also about having that scale whilst filling it with a fully realised world with multiple interactive objects, visual effects and complex physics. Whilst having better visuals is great, it's more in combination with the other benefits that extra power will give that we should be looking forward to.
Sticking with only visuals though, it's be great to see more titles that make proper use of tessellation and even just having higher resolution textures instead of the blurry textures we have on current gen games.








