In a nutshell, this mod:
- allows players to keep Yoshimo for the entire saga
- adds dialogue re: Yoshi's betrayal of the PC (his spying b/c Irenicus' Geas)
- adds an entirely new subplot for Yoshi with dialgoues and an encounter
- adds a Tree of Life dialogue for Yoshi
For those who have always wanted to have this option I think you will not be disappointed. It really is great fun to keep him for the saga. When I first did this (via use of a variable and a game editor, prior to the creation of this mod) Yoshi reached level 38 and became a backstabbing juggernaut.