Yup, all gameplay-related additions are free (maps, weapons, hinted at other features), while purely cosmetic content (characters) cost money.
That's a good way to do things. People who buy the character packs get no advantage over people who don't, and everyone gets the new free updates.
That's a good way to do things. People who buy the character packs get no advantage over people who don't, and everyone gets the new free updates.