One big reason the Fixpack update is so big is that previous versions couldn't fix problems in the engine. But with the help of engine guru scient, even the deepest bugs have now been fixed, like TNO's hit point gain and THACO and the entire morale system, which makes fear spells work as they should and Dak'kon's sword upgradable as it was meant to be. Lots of non-engine related fixes too... my favorite individual fixes are that turning the Anarchists in to the Harmonium now comes with consequences for your relations with both factions, and the Tenement of Thugs is now what it was always meant to be, a Thieves' Playground. And that's just the beginning.

Unfinished Business also has a lot of great new content. Among the restorations are 27 fully voiced flirts between Morte and female zombies that makes the game feel fresh and new straight from the Mortuary. Also, 9 restored creatures and dialogues in the Lower Ward, additional Mebbeth dialogue is restored, and even a new content mod that also restores additional original dialogue, the Expanded Deionarra's Truth mod, which has received strong approval from original PS:T designers :).