I downloaded the minute it was ready. Very impressed and performance impact is minimal. Little longer load times, but expected.
First thing you notice is NPCs. Improved NPC clothing is no longer needed. No More Blocky Faces is no longer needed.
Dwemer ruins look awesome. Everything is sharp. Lots of hi res texture mods are now obsolete, IMHO.
I'll be surprised if isoku's awesome mods for water and fire will be invalidated.
There will be a bunch of other texture mods that must remain...night sky, skill screen, etc.