RE: soap - the soap-making order, like rendering fat in a kitchen, does not always show up promptly even if you do have the materials sitting right beside the relevant workshops.
If you do change the soap reaction to produce bars, the dwarves will move it around, but they AND THEIR PETS will start spamming "cancels Clean self: Cannot reach site" and never dealing with it as soon as they get a contaminant. One time I had a cat doing that for a while, it seemed to stop(I think the cat got rained on) - and then 8 more things started doing it.
My personal worst so far:
Hot embark site. Nice flat land. Joyous Wilds. I dug down, found aquifer when I thought I was safely off that tile, dug over, dug down a bit more, broke into a cavern, had a little red c send my dwarves flailing as it ran up past them, out the ramp, and off the map. Walled up the immediate vicinity in the cavern, started farms and such, was just generally setting in. Got a promising migrant wave.
And then they ALL STARTED MELTING.
This wasn't even a scorching climate. Just "Hot." Most of the migrants and pretty much all of my animals died.
Having things go wrong, like the pathing issues and the nonfunctioning surgery, is merely irritating. Having my dwarves struck down by the fist of God eliminates any point in even playing. If I want to play a gambling game, I'm sure there are tons of poker sites that will happily oblige me.
So yeah. Biggest frustration: Spontaneous dwarven combustionliquefaction.
The new version has a lot of promise, and I'm not sure I want to go back to the old one; but things like that just... leach all the fun out of it.