Second volcano embark is moving along well; year 2, militia is fully iron-equipped and steel production is plodding along, limited by a complete lack of coal in the embark (having to use trees -> charcoal and whatever other coal is brought by the caravans). One ambush, various thieves, no sieges or megabeasts yet.
Couple of observations:
1) After screwing around in previous games with pumps, draining ponds, dealing with streams and flooding, etc, it is actually nice to have a small, controllable, infinite aquifer source about 20 z-levels below my main fortress to put the well over. And since the aquifer only covers the North-central quadrant of the embark site, digging below it is no problem at all. I think partial-coverage aquifer is going to be my preferred embark from now on.
2) Magma is *awesome*. I can't imagine going back to using regular fuel. I may go for volcano embarks for the forseeable future just to have an infinite high-altitude magma source (so I don't have to make massive magma-proof pump stacks or resort to system exploits like water reactors). Sand or clay + magma = unlimited trade potential (both available on this site; no fire clay or kaolinite yet, unfortunately, but you can't have everything). Something else I notice; having magma available invites the unquenchable desire to weaponize it. Main entrance gate overhead murder holes are now in progress (using artifact obsidian floodgate as the deployment method). Looking forward to the first siege so I can make some magma mist and !!goblins!!. Also looking forward to said !!goblins!! running around and setting my few trees on fire.
3) The game is watching me...after getting the aquifer access for my well, I drained my cistern off (to retrieve the body of a dwarf that had fallen down the well holding a useful artifact). To do this, I pierced a hole in my outer wall so the excess water could flow out and down the side of the mountain. Within seconds (real time) of breaching the wall, a goblin ambush popped up on the border nearest the hole and walked right into the passage to my forges. Intervention by the whole millitia solved the problem in short order, but not before three macedwarfs, one hunters, and a peasant were struck down. No resultant tantrums.
4) More than 3/4 of my migrant dwarves have combat skills (usually one weapon + shield, armor, dodger); I've been inducting everyone with skills into a squad, to the point that a significant majority of my population is also in the military. In previous games, only 1-2 migrants per wave has had military skills, and I've had to make do with a much smaller militia (and therefore longer training cycles so I have at least some dwarves armed, armored, and in predictable locations at all times). I have no idea what controls immigrant skills, but something is definitely different in this embark.