Old Stuff vs. New Stuff
Since the SRVU, new champions, and several VU's and TU's, the game seems alot nicer. I'd say the game pushed itself to 2015's standards, all while keeping everything looking nice and running smoothly. Until you see this.
Any item that was made in or past Season 4 has it's own flair compared to other older items. Some old items just reflect other items.
Ex. 
, or

Newer items compared to older ones-
,

This doesn't apply to only items. This applies to skins and champions themselves. Champions that haven't been visually upgraded are extremely lacking compared to others.
Ex.
vs 
Warwick is basically the big wolf from the old SR.
I'll also say that older effects which use older and likely more space-consuming files (ex. Nunu's ult) cause occasional frame drops, even on the computer I got myself literally 9 days ago. That really could change how a teamfight pans out.
I understand that these items and champions are likely under change, but it seems rather inconsistent currently. Once the PBE starts cycling again I'm sure I'll see more TU's and item updates. But by all means, keep it up, Rito.