Never ever order your soldiers to attack dwarven caravan guards/merchants though. It will lead to a loyalty cascade, attacking the guards makes your soldiers an enemy of your civ, but they remain in your civ so anyone attacking them becomes an enemy, and this goes on until there are only a handful of survivors left who may or may not be infected with the cascade, requiring isolation from the rest of the fort.
The blood spatter spread from early 2010 is gone, but you still should avoid puddles of blood when it comes to deadly blood FB's or titans.
There is now a mineral scarcity option in worldgen. Mess with it however you like. 1 is for encrusting your gold furniture with silver and jewels of all sorts.
Military control is now a bit better done, but requires some learning with the various parts, like you have to set the squad active after selecting what months they practice on in order for them to actually train or spar, rather than have individual exercise.
Hospitals work a lot better now actually than early DF2010. But your medical staff can still decide to go on fucking long breaks if they feel like it, so hire some useless peasants as Nurses to do healthcare as well.
Soapmaking by yourself is still broken when it comes to lye creation. Water in buckets ends up breaking the whole thing, so either have a burrow where all the buckets are kept, and never touched(save for the lyemaker) or import all your lye. Or soap. Someone said you can import soap directly, so yeah. Why should you bother? Soap is important in cleaning injured dorfs, lessens the chance of infection. Also, the previous bug with cleaning patients, with doctors standing next to the water source for infinity with a bucket in hand is fixed.
Create pastures big enough to hold your animal population, if they're grazers that is. In case you add more animals to the population, try and expand the pastures too. When they eat too much and start to run out of grass/moss to graze on, animals start to pack together where there's something to eat and attack each other.
Also, animals can attack dwarves in cramped meeting zones.
Eggsplosion isn't as bad as catsplosion. Eggs first need to hatch, which takes time and if you have a food stockpile which takes eggs, they're fetched far before they're ready to hatch by your dorfs.
I can't think of anything else that's changed for the new version during the past year.