The other arena mode is called 'Battle Grid' and it sounds more interesting. It basically lets you design your own combat encounters by dropping enemies onto a grid. In addition to choosing which enemies go where, there are difficulty modifiers, and two enemies that don't feature in the campaign—Cal Kestis and Jaro Tapal—can be fought.
There's also a New Journey+ mode, which lets you replay the game with most collectibles and upgrades already unlocked. New cosmetics for Cal and BD-1 are also part of the pack, which should be available now. Here are the full update notes.
If don't have Fallen Order but do play Fortnite, a bunch of Star Wars loot is available right now, and probably not for too much longer.