The soul-sucking was really a problem when I tried to roleplay as an evil character... as a good character it was almost trivial. A very bad design decision by Obsidian, imo.
I must be one of the few that found the mechanic interesting...
Personally I enjoyed Storm of Zehir the most... it reminded me of Icewind Dale & Baldur's Gate with its free-roaming.
I think what I liked about Mask and Zehir is in many ways, they're so different. Mask has that PST feel going on (somewhat linear world w/ a deep, strong dark-story and lots of decisions to make to alter the story), while Zehir has the BG and IWD feel going on w/ the open-world.
Yeah, I loved the free-roam of Zehir and its new gameplay elements...
...But really, I think the story suffered in depth and the NPC's suffered with a lack of character depth. I bet this is something say a modder could really go crazy with and really improve that aspect of things.
Still, a very good expansion, if you ask me. Spent a good deal of time w/ it.
