Personally these things are what I'm looking most forward too.
Health care up to the point that a dwarf can generally pull through what should be non-mortal trauma
Simple surgery/setting of breaks/etc.
Make dwarves clean themselves up and groom/trim their cosmetic tissue layers before they sleep
These issues have always been a bit 'nagging', always having the same two dwarves with yellow spines lying in the barracks for years and years.
And the 'dirtiness' of the dwarves also has been a small nagging thing for me. Nice to see them resolved.
Possibility for unending attacks
Underground feature resources more likely and useful (farmable areas, etc.)
Easy to find features (if you want lots) throughout all Z levels, arranged to permit ample area for a fortress
One of the things dearly missed from the 2d version is the possibillity of sudden ambushes from the chasm as well as the spontaneous monster generation in the deep mines. (anyone else remember what creature it was that sometimes appeared and killed your miners? I want to say trolls but..)
Caves.
Everything about this. Currently caves have unused potential but are mostly a nuissance/irrelevant to gameplay.It is my hope that these updates will pan out to something much more entertaining.
Entity positions.
It will be interesting to see how the updated formalised hierarchy of the Fort will pan out. The change from 2d to 3d also brought new ways and positions and there was some excitement about that if I remember right.
I wonder what 'update guards' is about?
Weapon rack and armor stand assignments to individual soldiers within the barracks (automatic or manual if you care)
I have a question here. Will the units actually USE these? Hanging up their gear and switching to civilian clothing while of duty or what?
Commander-led training, with commander and evaluation of pupils determining nature of sparring/routines
Associated skills for leading/teaching
Personality effects on training
All this makes individual traits more important and I consider this a very interesting development that may change the focus of many gamers away from the whole 'equipment' side of the equation to are more 'individual dwarf' oriented view.
Gonna be interesting if it works.
Some more incentive to getting to know your dwarfs.
Soldiers that are standing down should sort out their equipment according to their settings, trading up if proper, generally sort out their belongings
A longed for improvement. I have found that in longer running forts I can deal with all clothing issues EXCEPT the way military and guards handle theirs. It will be nice to see a resolution here.
Updating undead severs (might not be necessary)
What? What are undead sewers?
Fix the annoying cat bug
What is this bug? How does it manifest?
Lots of other really interesting changes, I wonder how long the bug sqashing period will be.