Galandil does recommend you explore the redesigned keeps with a fresh character to avoid conflicts and bugs with previous save files. As the description on the Nexus download page says, “the aim of all of this is to create a more memorable and diverse experience, making the cities actually feel like cities hopefully without ruining the natural and realistic design of the vanilla game.” Sounds good to me. What I like about this mod is that all of these changes are designed to smoothly fit with the look and lore of the game, unlike a lot of other mods that just make everything sparkly or crazy-magical.
There are also new settlements scattered around some of Skyrim‘s more austere areas to liven up the experience. Cities such as Falkreath, Dawnstar, and Winterhold all get some much needed TLC with added vendors, improved buildings, and more impressive holds and courts.