Personally, I liked the changes to the city-states in Dark Sun Revised (DSR). In the original setting, all the city-states were mostly alike ("City ruled by immortal sorcerer-monarch served by corrupt templars"). In DSR, you got seven really different city-states:
Tyr - fledgling democracy.
Urik - pretty much as before, but closed to the rest of the world.
Nibenay - pretty much as before.
Gulg - pretty much as before but the SQ *seems* to become more ecologically-minded.
Raam - descends into total anarchy.
Balic - ruled by three merchant-lords of varying dispositions.
Draj - pretend it's business as usual with a figure-head king.
To me, that's much more interesting than seven city-states that are pretty much alike. For those who want to run a city-based campaign where the PCs struggle against the sorcerer-monarch's henchmen, there are still three cities for that (two of which were pretty well described in The Ivory Triangle - that's probably why those two particular monarchs survived).
Personally, I disliked the rule changes in DSR more than the setting changes: halflings suddenly can't be preservers/illusionists anymore, different (and worse) psionics rules, defiling on memorization, and where the heck did the templar class go?