When Diablo 3 originally came out. I really enjoyed the game just on it's own. But after awhile I started to feel like what I was doing was pointless. Just doing the same thing over and over to get better. And while the original game was fun, the new Reaper of Souls expansion really is the icing on the cake. Quite a few things have changed since the expansion. The difficulty modes, Normal, Nightmate, Hell, and Inferno. No longer exist. Now the difficulties follow a much more efficient and better thought out system. Essentially the difficulties are the same there are just more of them, allowing you to cater the difficulty to the gear your character has and it's level. Another BIG change is the auction house. While in the vanilla game, the auction house was near crucial to leveling and getting good gear, it also made it easy to "buy the game" so to speak. Which arose alot of "Is it pay to win?" Questions being asked. Which is what I believe to of been the driving reason for the change in ROS. The last crucial change is that, since the auction house is gone, getting good gear is more possible with the system Blizzard is calling Loot 2.0 which fundamentally keeps the loot the same just with higher chances for better gear. Which really improves the game.