This being Destiny, there are lots of cosmetics. You can earn Chocolate Strange Coins to buy masks (including for Shadowkeep characters like Eris Morn), add skeletal armor ornaments, pick up Halloween-themed Ghosts and find similarly festive Sparrow vehicles.

There aren't any radical departures from D2's formula, but that's not necessarily a bad thing. The Festival of the Lost is one of the longest-running seasonal events in Destiny as a whole, and frequently the silliest -- it's a chance to cut loose in a game that occasionally takes itself very seriously.