Dwarf Mode:
Dwarves have needs now. They'll work better if they're able to meet the most important of their needs. This involves building taverns, temples and libraries which dwarves will hang out in instead of going 'on break' or 'party'.
Taverns, temples and libraries will attract visitors from your neighbors. Mercenaries, scholars and entertainers mostly, plus those who just want to hang out with the sexy bards (like the local bandits for example).
Visitors can be of any race that lives nearby. Goblin dance troupes will turn up from the local dark fortress at times, but generally goblin visitors are those that live in nearby human civs. Outside influences, wars and other unknown factors cause them all to erupt into mindless violence every so often.
People hanging out at the tavern may end up in fist fights that the captain of the guard is ignoring for now. Generally this is caused by escalating arguments. Some dwarves like to argue. Goblins really like to argue. Some people don't like to argue and will punch insistent arguers to death. By mistake.
Taking of death, tavern goers may kill themselves drinking nowadays. Don't worry about it.
Art, poetry, music and dancing now exist in the world to give dwarves something to do at the tavern.
Workshops can now produce armour to fit any size of visitor you happen to have. Elephant-man steel plate probably uses a lot of steel.
The manager is now a highly sophisticated crazy workflow system. Seems to mostly work.
Adventurer:
With the new arts introduced, adventuring as a bard is possible. Dance, sing, write books, visit libraries, argue and get killed.
Arguing with people can change their values.
People recognise your good deeds and groovy dance moves a lot more (reputation improvement is now more apparent, killing bandits isn't murder).
Hearths give kill quests.
Adventurers can build buildings, carve bones, cut down trees and make stone axes.
Animal man tribes can civilize during worldgen by joining nearby civilizations. You can play as any race that lives in a human, elf or dwarf civ (animal-men, goblins, plump helmet men, gorlaks). You can also choose any non-civilised animal man you like and you'll be placed in a civ.
I guess there's a lot I missed. Anyone else want to pick up?
--Oh, almost forgot. Sieges work now (they don't get lost trying to find your fortress). Goblins ride beak dogs and you can set a cap on invaders in the options.