What UOR Got Right
For PvE'ers
UOR removed many (but not all) of the ways players were able to grief one another without breaking PvM combat. Removal of mobile blocking is a grey topic, as it also removed some of the strategy and tactics in large-scale PvE battles and certain dungeon areas.
Doubling the landmass (and PvE content therein) eased competition for that content.
For PvP'ers
Factions enabled large-scale PvP combat with specific goals without stat loss or other punishment.
For Everyone
Passive gains for secondary skills (eval, anat, etc) was just a good idea all around. Who in their right mind would actually use Evaluating Intelligence 10,000 times without macroing it?
What UOR Got Wrong
The primary failing of UOR (and in fact of the history of UO development) is that they were still trying to cater to two incompatible play styles on the same server at the same time: PvE / PvP and PKs. Trammel gave players a way to opt-out of being a victim for PK's (for those that chose to be victims in the first place

I think if the UOR had simply been a change to a PvP and non-PvP server model things would have worked out a lot better. Sure we had SP, but as long as the red PK model existed on other servers and there were plenty of non-PvPers to gank, this style of play was going to stick around. And unfortunately this style of play was persecuted with every expansion, until it became untenable.
Thoughts?