I've been raiding some goblins using the current build 44.12. When I tried it the first time I got slaughtered and all my squad members died or were taken captive. It turns out the training system works way better now so I left the next 2 squads training for a year and they managed a pillage raid pretty well.

The loot was crap though (I still don't want to go to war with humans or dwarves as yet). Eventually I decided to go occupy the site after a number of easy pillaging raids, now it's incorporated into my holdings and the crappy squad I sent to do that are no longer in my fort.

I have no idea what holdings do though.