I'm in the third year of my second .40 fort and I'm cautiously optimistic. Some observations:
* FPS appears to be hit significantly; I'm dropping below 100 (my max set point) by the first immigration wave, previously I hadn't seen that until my population was over 100.
* Weapon traps seem to be a lot less effective; I used to be able to defend a fort by a very thin layer of traps (often just one or two traps thick) with iron serrated disks and spiked balls. When I waited for the first siege to walk through, the lead soldier walked right through two traps without triggering them and kept going.
* I started at WAR with the local goblins, and saw no ambushes before the first siege in year 2. It was about 10 enemy soldiers, with about half of those being kidnapped dwarves and elves (not from my fortress). I made the mistake of rushing my army out after them when they started to retreat and got seriously bloodied (my soldiers were a bit under-armored at the time since I had deferred making armor until I started my steel industry).
* External world events add some level of interest. The world news from the outpost liaison was pretty depressing; the local goblin civilization had overrun three nearby dwarf fortresses in the previous year. Right after the conversation, three of my dwarves inherited the title of Baron one right after the other, presumably because of the deaths of the nobility in those cities. That came as a bit of a surprise, so I'm scrambling to get them appropriate quarters.
* My dwarves are emotional wrecks. I'm seeing lots of work cancellations due to Horrified! and Emotional Shock, and my Justice queue is full of civil disorder allegations (although no one is showing up as witnesses, which is strange because the perpetrator usually punches the victim a few times but leaves them alive).
* The dwarves comments about their emotional state in the combat message queue adds some color. On the down side, it appears that sparring now just shows up as normal combat (I haven't seen a blue "S", and most of the red "C"s have been military dwarves "lightly tapping" each other).
Overall it does seem a bit easier, especially with the vast amounts of wood available and the wide array of new plants, fruits, vegetables, and so forth (easier to have a broad array of food and alcohol to prevent boredom).