The new SR looks like a bad version of Dota 2: The Monotone Dust Problem
First, a Reddit thread has captured the issue and has great comparisons of how lifeless/dull the new map looks in comparison to the old.
http://www.reddit.com/r/leagueoflegends/comments/2m78ax/new_summoners_rift_feelsempty_examples/
For just the visual comparison: http://i.imgur.com/bQU8AbW.jpg
It looks like they tried to copy Dota 2's art style, but removed the nice detail and color that Dota 2 has. Frankly, I am hugely disappointed by the new map. Big empty textures that look as interesting as worn pavement. The new maps looks dead. The bustling, happy, almost cartoony good looks of the old map are gone and replaced with monotone dust.
However, despite the huge letdown that is the new SR, some bright people have managed to make it look much better with some tweaking and added color saturation.
http://postimg.org/image/b8udgztiv/
I for one think that the above image is a HUGE improvement over the monotone dust that is now available in team-builder. Please Riot, add some saturation control or something to make the new SR look more like the above image.
Edit: One more image: http://imgur.com/YHBVaCh,rzUH5zP,xquQhrl,bzUdxE0#0
All credit goes to EntityZero over on Reddit for showing that the new map CAN look good with some tweaks.