Think up the worst feature? Why?
I guess perma-death. Character dies then you have to start from scratch. That would svck.
I can think up better features I'd like to have!
Like: Occasionally our characters getting knocked out. Then while you're knocked out you get robbed or captured rather than just getting killed. This could also be a great addition to the radiant quest system. Getting captured could then be a way of discovering certain locations which otherwise you wouldn't find, and those areas could contain powerful weapons or other items.
Imagine getting knocked out then moments later your character opens their eyes and is in some dark cave with nothing!
That would be fun