If you brought the season pass, you'll want to know what the newest DLC is. Batgirl's pre-Arkham Asylum adventure is out today for Season Pass holders but next months (or possibly part of next months DLC) has been announced.
Next month you can get the Michael Keaton suit from Tim Burton's version of the Dark Knight, which also includes a Batmobile skin. Also a pack of "The Family".
This includes a new 1990's Catwoman suit, a robin suit which is a year after Arkham Knights events. Nightwing from the Arkham City. Batman in his Adam West style black and grey suit, Year One Batman and Arkham Origins Batman.