Dwarves:
-Pro: Fits of intelligence, can be brilliant tacticians and fighters. Craftsmanship is unparalleled.
Only race in Vanilla that can sustain a settlement without outside contact.
-Con: Fits of stupidity. Frequently do things that make their hive-mind baulk at the stupidity, eg. rushing blindly into a siege just to steal socks, immuring themselves behind walls and starving to death, killing each other because they're sad, punishing dwarves for being unable to fulfill an order due to lack of resources...
Humans:
-Pro: Brilliant fighters, good friends, great tactical behaviour. Good to trade with. No silly requests.
-Con: Not many cons. They lack the entrepreneurial spirit of the dwarves and their craftsmanship, but they are vastly better than the other races.
Elves:
-Pro: Can tame animals that no other race can. They do not plunder the land.
-Con: They try to enforce their beliefs on other races. They are extremely stupid to fight with wooden weaponry. They become outraged over the treatment of trees. They consume the corpses of vanquished foes, which enrages any other race. One would think that they would be able to refrain from this to be able to strengthen diplomatic relations. They trade awful crafts.
Goblins:
-Pro: They have enslaved other races. The only other race to do this is dwarves, and then only if they manage to catch Tigermen. They are valiant fighters, and they know when a fight is lost. They understand psychological warfare.
-Con: They don't seem to be able to make very good armour or weapons. They blunder at a wall and fail to recognise traps that they potentially could've been hit by.
Kobolds:
-Pro: Their cuteness moves some dwarven hive-minds to adopt them as mascots and try to breed them. They wisely only assault forts with thievery.
-Cons: They are so thick as to forget to eat sometimes.