Yes, you read it right, everyone inside darkness attacks normally (because they have both advantage + disadvantage).
It would make more sense for everyone to just have disadvantage, but it could have been done this way intentionally, so it's not just a miss-miss-miss for multiple turns.
Plus, as said, Warlock with Devil's Sight is absolutely ROCKING in Darkness. And because Darkness travels on an item, you can cast it on your pact blade / hat and carry it with you. Or even cover the item, if your partymembers would like to actually see something.