Some preliminary findings:
Dwarves are now much more detailed, in terms of personality and appearance. This is cool.
All stones are now "economic" and can be selected or forbidden via the (z) menu. This is good.
The default embark size is now 4 by 4, presumably for performance reasons. Embarks might have shrunk in area, but they make it up in volume. My current embark region, for example, has a bottom of -159 z level. This is cool.
Dwarves will now not drop what they're doing if they're hungry, thirsty or tired, and will try to finish the job first. Not sure if this is good, thus far I haven't had any workaholics drop dead from thirst yet, but they do get the negative thought from being hungry, thirsty, drowsy etc.
Slight interface changes: Space is no longer the "cancel" key, it's now escape. This can be changed in the config files though. A dwarf's jobs are now grouped together in sub-menus, for example Carpentry, Crossbow-making and Wood Cutting are under the Woodworking menu.
The game no longer auto-pauses and zooms to the location when you strike something while mining. This is good, no more alunite and microcline spam.
New jobs, quite a few of them. This is probably good, though it does mean my preferred embark profiles will need tweaking.
No major bugs or glitches encountered so far, seems like Toady did a thorough job debugging. So far so good!