Note its Jelly bean and will convert your E980 to a E980H, i dont think that makes any differences personally
so i used this guide and flashed it http://lg.storagecow.eu/?page_id=12
tweaks i did and highly recommended.
1. Root using universal root http://forum.xda-developers.com/show....php?t=2362657
2. use Titanium backup to remove/freeze unwanted apps
3. Use greenify to force sleep apps that cause wakelocks ( Greenify is free app in the market)
4. Use Xposed + Gravity box to tweak looks + add data traffic counter and double tap to sleep
5. Enabled eco mode for Quad core ( in settings )
I am seeing battery life thats just amazing , 1 % battery loss overnight while asleep , this is my goto rom until official KK is out
Plus max internal storage available, free ram is about 800-900 mb on boot , that could be bettered, but im quite happy overall
This gave me far better performance and battery life as compared to the KK leaks out there, and oh yea no bugs like the speakerphone not working Ive posted in General as this isnt a custom rom per se, just the official unbranded with my tweaks.