I took the OP's question to be more like asking which changes had happened that were the biggest and most important seeming to us (since there have been soooo many!), so here are things that come to my mind . . .

- Crafting: more streamlined process. Way fewer clicks!
- Repairs: repair icon added, makes getting repairs so much easier. Also durability has been increased a ton for items that are the correct rank/class for you. Overall repairs are not a big pain like they used to be.
- Markets: you can search the wards now, plus you get two free retainers instead of one
- SP gains: they have tweaked it more than once, but it seems to be in a good place now IMHO. Parties are definitely favorable.
- Notorious monsters: a few have been added. A fun thing for those at/near the cap to to do in groups.
- Population: sadly it is quite small compared to how it was in October. And if you're not in Thanalan good luck finding people to play with! ;_;