@hanni79: As far as I know, dwarves are actually fairly good at eating things that are on their preferred list. HOWEVER, there are a number of bugs and a lingering misdirection in DF.
- It used to be that the meal quality was important. Now, however, the quality has an effect only if the meal contains a favorite ingredient (misdirection).
- DF lies about what favorite ingredients are for animal products, saying Cheetah, when the actual ingredient required is Giant Cheetah Eye (the description does not distinguish between giant or regular (or, in fact, animal people when it comes to milk), and it does not point out the detailed item. Exactly the desired thing is required.
- DF generates preferences that are physically impossible, like body parts of vermin and body parts that can never be acquired by butchering an animal because the animal isn't large enough you yield that part.
- DF generates preferences without regard for whether it has actually provided that creature in any biome in the world.
- A lot of plants are bugged so they can't be farmed sustainably because you can't get seeds from them (seeds can occasionally be gotten from caravans, as can impossible body parts).
I've probably missed to mention half of the issues, but the bug tracker has all that's known.
Edit: Something completely different:
The dwarf need satisfaction decay rate is way too quick, in my view. Trying to deal with trouble dwarves, I give them time off, see that they got a need to craft, arrange for the crafting of an item: Happy, but only for a month or so before it's down to brown again, which leads to constant micro management of your grumpy buggers. Add to that that to get anything out of military training, they'll have to be at it long enough to learn something, which seems to frequently be a month, and not getting anything out of that time isn't uncommon either.
Another problem with the rapid decay rate is that you can't really plan any R&R activities so their friends (if they've managed to get any) might be off at the same time as a mitigation strategy. I've been trying to keep a yearly schedule with spring for agriculture, summer for fruit harvesting, autumn for catching up on jobs fallen behind (mostly hauling), and winter off for R&R. While the dorfs are better at recognizing each other in this release (all of them have acquaintances to several others after 4 years), the friend making is decidedly poor still.
They can also go from fine (less than 1000 stress) to 24000 stress in less than a month if caught in (harmless) freakish weather repeatedly while felling trees (despite liking being outdoors). The only indication is the red arrow you might see if you happen to look at that dorf.